First, welcome to the DIS Collectors Board, Tracy.
Yes, pin trading is a fun thing to do at WDW. It can also be an expensive thing to do if you're not careful.
A good place to start is the Pin Trading 101 page on the main wdwinfo.com site. It's a good primer for the rules of pin trading with CMs at WDW. Also, I've compiled a FAQ list for pin trading here on the Collectors Board, covering the basics for trading online (especially on the DIS) as well as a few more hints for the parks. Links to both of these are below.
You can also ask any questions you would like here on the board. We have an outstanding community of traders and collectors that are willing and able to help.
Finally, there are other sites devoted to Disney pin trading. Dizpins and Dizneypins both feature news and information on pin trading, and Pinpics is an extensive online directory of Disney pins. All three of these sites are unofficial Disney sites and links to all three of these are in the FAQ. This weekend Disney is premiering their official Disney pin trading site at officialdisneypintrading.com.
Hope this gets you started.

When is your next trip going to be?