First, go to your county page, and hit the Wiki tab. Then log in as Ronnie says. Then you can either hit the Edit link on the left in Bold Blue, or just the individual section. You will see and edit on the right next to the Bold Title of the section. This is the safest, as you only work on a small part of the page. Make the changes and hit the save at the bottom.
http://wiki.radioreference.com/index...ounty_%28MO%29
Edit
Since Mike beat me to the punch on this, you can tell the things that are brought in automatically from the Data Base because they will be in formated tables identical to the DB. The other items may or may not be in the DB, but you can always edit them anyway, and submit confirmed info to the DB as well like Mike said.