What do I need to (and to know) become a web designer or/and a web developer ?

The best way to get training is probably through your local community college. Check their website and see if they have a program in web design. If they do, visit the school and find out more.

I am sorry, I know this is going to sound very harsh but it is for your own good. I know I hate it when people say that but it is usually true. If you actually have no idea how to start this endeavor, then you have a long way to go. And no, you cannot do this to get money quickly. People will expect you to do a good job and you won't get paid if you don't...it is not an overnight learning process. People who do this are talented and have either lots of experience, lots of training, or both. In fact, if you don't do a good job, you could be sued. This is not a job at McDonald's where if you don't do good you get fired and so what...this is people's hard earned money and they will expect a professionally done job. The training takes at least 18 months and frankly, if you can't even start the research on how to start without asking a social network for help, you have a ways to go. I get the impression you are very young so you probably have a reason for not knowing but the first step in becoming independent is to learn how to gather information on your own and what is appropriate to ask for help and opinions on. Again, I know I may sound mean or harsh but I am not trying to do this...I am just trying to help you see that this is to be taken much more seriously. If you are truly interested in this line of work, then you can do the research for yourself. You obviously know how to use the internet so you can do this and then you will feel much more accomplished about what you find out and what you can do. I do wish you good luck!