I want to create a links from my website to other company websites that are relevant to my site.?

In a certain sense, information on the internet is considered as information in the public domain. As such, permission is not required to link to a web page that displays this information. In fact, this is usually welcomed by the target website, since search engines look upon these links as "votes of confidence" and assign value to this practice, which in turn influences search rankings. On the other hand, if you have too many outbound links to other sites, this can dilute the value of those incoming links that point to your site from other web pages. This has special significance in relation to your home page. It is best to create a separate page for these outbound links, rather than linking directly from your home page. That is why you often see websites with a page designated specifically as "Links."

No. You only need permission to use their images, logos, etc.

To contact them and ask for permission would be a quite polite and honorable way for a webmaster. You can do so but you must not. All the can do is asking you for removing the link to their websites, but if content is relevant I wouldn't believe that this could happen.

WHAT!!! No, no, no. You need to: 1) Place\Type the web address where you want it to go 2) Select the web address 3) Right-click and select 'Hyperlink....' 4) Type the web address in the internet hyperlink section 5) You are done! LOL!