I live in St.Louis, Missouri. How would I find a local USCF tournament in my area? Would I get a rating? How does their rating system work, is there a certain rating I would start at?

great questions! i'm working on getting people to start posting events in the CHESS EVENTS section of the site. right now nobody really knows about it, but in the future i hope that all chess events will be posted on chess.com! 

You should find a local chess club.  Most chess clubs will have a USCF Tournament Director (TD).  As soon as you play 5 tournament games you will get a provisional rating (not as accurate), and once you get 20 or 25 games in you will get a real rating.  Good luck!

You most chess as soo as you play more then 10 tournament games (you most be provisional rating) then you will luckly real rating most of one.

You can just go to the USCF website http://www.uschess.org

Also to consider is what your motivation is for membership. There are annual dues for the USCF. If you are just looking to get better at chess, you could use that money for some good chess books, and hop on to http://www.freechess.org to play some online chess in a more serious atmosphere than yahoo.com for example. Tournament chess has it's plusses, but your time and money may serve you better in other ways. Keep in mind that there is a difference between chess rating and chess strength. Ratings are often superficial numbers that we chess players toss around to feed our egos, so just make sure you are wanting a rating for the right reason. Tournament chess IS fun, but just make sure you don't let your rating DEFINE you as a chess player. Just focus on your enjoyment of the game and your own progression of skill. Now that I really don't care about my rating, I get much more out of chess. I hope this advice is helpful to you.

Mr Mike

Follow Chessroshi's advice about the USCF website, or search for a local chess organization (city or state). The USCF can also help you find a club or become a tournament director yourself! I believe you need 4 games for a provisional rating (USCF), through game 25 when it becomes a regular rating. A lot of tournaments will even have a setion just for unrated players.