As has been mentioned, checking out the listings for Illinois on Witchvox at http://www.witchvox.com/vn/hm/usil.html is a good place to start.
That having been said I will add this caveat since I don't know how old you are. If you are under 18 it is highly unlikely that any coven will accept you as a member without the consent of your parents. This isn't because teens aren't capable of doing the work that a coven requires. It has to do with particular laws in the United States that forbid anyone but a parent to be involved in the religious upbringing of a minor. Any group or individual that does so could end up with hefty fines or even jail sentences.
If you wish to read more about why this is so you can find it at http://www.spellsofmagic.com/read_post.html?post=556828
By the way, please refrain from using text speak in your posts, it is violation of site rules.