Hello,
Check out this link:
http://www.centos.org/docs/5/html/De...-wireless.html
Specifically, are you sure your wifi card has been recognized? Check to see that you see the device. Worst case scenario, you can hit the command line and lspci and check to see if the device is listed. (or, if it's a USB wifi stick, lsusb)...
Please update your progress!