Do I need an attorney to get a provisional patent?

The "provisional patent" is something that is never granted. You can't get a "provisional patent". You can file a provisional patent application. This gives you primarily two things. 1) A date that you can put on your non-provisional application for a patent later, and 2) the legal right to claim patent pending. A provisional patent application  is not examined by the patent office, it will not be reviewed or published without further action by the applicant, it will not ever eventually become a patent. Think of it as a placeholder that lets you claim an effectively earlier filing date on a regular (non-provisional) application for patent. With that being said, if you wish to get an attorney to help you file the provisional application, ask him to at least write the claims in proper form, an enabling description, a preferred embodiment of the invention, and some drawings or illustrations.

No you don't need an attorney or this mob you mentioned to file.  It sounds like you're acting as an individual and as such would likely be eligible to file as a micro entity. I can't remember the exact cost but I think this will come in at about $60. You do have to be registered but you do that during the fileing process. You can do a patent search at google patent and find similar patents using key words. This is usefull for research and making sure you include everything. The hole patent area is very complex and depending on where you want to go with it there are different strategies. After you file the  provisional I recommend using an attorney but you'll have twelve months up your sleeve before then. It's a headache but information about registering, micro entity status etc can be found on the us patent web site.

I recently submitted a provisional patent and found it simple and straight forward. As mentioned by previous responders, all that you are doing with ppa is to lock the submission date, incase someone else also thinks of the same/similar idea.

There is no prescribed format to draft provisional patent applications. An inventor can just write down how his invention works and thereafter file a provisional patent application. Following this strategy, undoubtedly saves money and helps in obtaining a priority date, but it has many cons as well. Most people fail to advice inventors that, a non-provisional (complete) application which is filed after filing a provisional application, is based on the provisional application and has to be within the scope of the provisional application. It is therefore advisable to draft a provisional application with the same vigour as a non-provisional application. If the provisional specification is not drafted well, there will be serious limitations as to drafting a complete application based on the provisional specification. The provisional specification has to go into minute details of the invention. Drafting a provisional specification by a person who is not well versed with drafting patent specifications, will certainly affect the level of protection sought by the inventor.   Link provided below will provide a better understanding as why do one has to seek help from patent professional to file a  provisional patent application. http://www.invntree.com/blogs/should-inventor-take-professional-help-draft-and-file-patent-applications

I'm late to the party, but I think you should at least consider whether or not you need a foreign filing license to file first in a foreign country.   People in the US, and in the UK do, and I suspect you might have to in South Africa.    Basically, a check to see that the invention isn't related to any military or cryptographic technology, etc.   And since your invention is software....  Here's the US statute... better check to see that there isn't something similar in South Africa: 35 U.S.C. 184  Filing of application in foreign country. (a) FILING IN FOREIGN COUNTRY.—Except when authorized by a license obtained from the Commissioner of Patents a person shall not file or cause or authorize to be filed in any foreign country prior to six months after filing in the United States an application for patent or for the registration of a utility model, industrial design, or model in respect of an invention made in this country. A license shall not be granted with respect to an invention subject to an order issued by the Commissioner of Patents pursuant to http://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html#d0e304551 without the concurrence of the head of the departments and the chief officers of the agencies who caused the order to be issued. The license may be granted retroactively where an application has been filed abroad through error and the application does not disclose an invention within the scope of http://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html#d0e304551. .... 35 U.S.C. 185  Patent barred for filing without license.Notwithstanding any other provisions of law any person, and his successors, assigns, or legal representatives, shall not receive a United States patent for an invention if that person, or his successors, assigns, or legal representatives shall, without procuring the license prescribed in http://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html#d0e304599912, have made, or consented to or assisted another’s making, application in a foreign country for a patent or for the registration of a utility model, industrial design, or model in respect of the invention. A United States patent issued to such person, his successors, assigns, or legal representatives shall be invalid, unless the failure to procure such license was through error, and the patent does not disclose subject matter within the scope of http://www.uspto.gov/web/offices/pac/mpep/mpep-9015-appx-l.html#d0e304551.Most of us don't think about this, because we first file in our country of residence, and the export review is done at the patent office of first filing as a matter of course; the foreign filing license is usually just a form paragraph on the Official  Filing Receipt here in the US. 

Wow - congrats on inventing something at such a young age! The answer to your question is no; you do not need an attorney for a provisional patent. As Konstantinos mentioned, the USPTO has a ton of http://www.uspto.gov/learning-and-resources/inventors-entrepreneurs-resourcesfor inventors. Information on the USPTO Patent Pro Bono Program can be found http://www.uspto.gov/patents-getting-started/using-legal-services/pro-bono/patent-pro-bono-program. To answer another question of yours - yes you may file online by clicking http://www.uspto.gov/patents-application-process/applying-online/about-efs-web. I suggest you check out a step-by-step guide for filing online found on this http://patentfile.org/filing-provisional-patent-at-uspto/. It provides screen shots of the application to walk you through the process.I noticed you are also from South Africa. If you have any questions regarding filing a patent application as a non-U.S. citizen then check out a past of mine in response to - Can a non-US citizen apply for a Provisional Application for Patent in the US as Inventor ?Lastly, you should take a look at https://www.lawtrades.com/?t=quora where we connect inventors with experienced patent attorneys for a living. Because inventors have needs specific to their respective product, we customize services and pricing to fit your budget. I think it would be in your best interest to get a free, on-demand price quote to see for yourself just how affordable we are. Feel free to message me with any legal questions you have specific to your company and/or invention. Good luck!