First off, I would like to personally welcome you to Wikipedia. Its good to see there are still people out there discovering this wonderful source.
Now to answer your questions. I have placed two templates at the top of your talk page which should provide you with some helpful links. Writing articles is fairly simple in wikipedia. You simply hit the "edit" tab at the top of your screen. A few pages, such as the main page, you cannot edit because only site administrators can, but for the remaining 2 million pages, you can edit them. Its quite simple...you simply copy paste out of Microsoft word and paste the content here. You will need to modify the formatting slightly, but that shouldn't be a problem. I strongly suggest you look at Wikipedia:Tutorial to learn more. Do be aware that articles should have reliable sources/references, and that they should have some notability(an article about your third-grade teacher's sock is not notable).
You mention that English isn't your first language...but not to worry, there is a Portuguese encyclopedia at http://pt.wikipedia.org/wiki/P%C3%A1gina_principal . If you feel your english is too weak you can contribute there...or if you feel your English is decent, you can help translate articles.
I would also like to suggest you seek "adoption" by a more experienced editor through the Wikipedia:Adopt_a_user "program"...see Wikipedia:Adopt-a-User/Adoptee's_Area. If you have further questions, feel free to ask me.
One last thing, when you leave a message, you can sign it by adding ~~~~ to the end of your message. Enjoy your stay at wikipedia and feel free to ask me if you still need help.Smallman12q (talk) 20:15, 11 March 2009 (UTC)Reply