Hi, Freexavier. Welcome to Wikipedia! I noticed you've just joined, and wanted to give you a few tips to get you started.
You don't need to read anything - anybody can edit; just go to an article and edit it. Be Bold, but please don't put silly stuff in - it will be removed very quickly, and will annoy people.
Ask for help. Edit this page, put {{helpme}} and describe what help you need. Someone will reply very quickly - usually within a few minutes.
Edit existing articles, before you make your own. Look at some subjects that you know about, and see if you can make them a bit better. For example, Wikipedia:Cleanup#2009.
When you're ready, read about Your first article. It should be about something well-known, and it will need references.
Good luck with editing; please drop me a line some time on my own talk page.
There's lots of information below. Once again, welcome to the fantastic world of Wikipedia!