Heres a link to the index(s) that each fund tracks. These are the same as the charts you see at the bottom of each page here on the site. In order C, S, I and F.

http://finance.yahoo.com/q?s=^gspc,^dwcpf,EFA,agg&d=t

The I fund has a lot to do with the dollar. I'm still trying to figure that one out.

The F fund has to do with bonds and their yield. Still working on understanding that one too.

http://www.investopedia.com/university/bonds/bonds3.asp

Some say that the small cap stocks (S fund) rise before the large cap stocks (C fund) during a recovery from a recession...heck if I know.

Theres a lot more to this than a couple of questions can answer. It's been quite a steep learning curve for me and I still don't know what the heck I'm doing. I'm just trying to answer as best I can because new people show up here all the time and ask the same general questions.

Read all the Account Talk threads.
Read the Day to Day Market Talk threads.

Read Tom's Market Comments every morning.
http://www.tsptalk.com/comments.html

Buy books about investing, follow links to articles. I like http://investopedia.com.

Hope that helps and good luck!