The general recommendation is to not do this.  However, if you just want to try it out, here are some sources for general information.

http://www.startbitcoin.com has some nice introductory information.

You will need to download a wallet from http://www.bitcoin.org.  This download will potentially take a long time.

ASIC miners (Application Specific Integrated Circuit) have taken the place of GPU miners.  ASIC miners are generally expensive and can become dated very quickly.

http://www.butterflylabs.com has some ASIC miners for sale at prices starting at $50 (not recommended).