On every article, in the left-hand sidebar, there is a link "Cite this page". Use it for each article that you used. That page will give you all the bibliographic data you need (including a permanent URL for the version of the page you used) and automatically generate citations in a number of common formats.
It wisely gives the author as "Wikipedia contributors", since many Wikipedia articles have had a great number of editors work on them—a complete list would be cumbersome. I recommend that you just use "Wikipedia contributors". If you really need a complete list, go to the article and use the "history" tab at the top of the page. Then, use the "Revision history statistics" link, which will list each editor of that page to date, ranked by how many edits they've made to the article. Editors with names which are 4 numbers from 0 to 255 separated by periods (e.g. "127.0.0.1") are the IP addresses used by anonymous users, and the list will mark them "anon" or some such.
I'm a volunteer administrator on Wikipedia. I see this question on Yahoo! Answers a lot—too bad there's no way to create a page with FAQs! :)