[stevedusa]

I don't think you need to select the cert once you have it installed.

Is it a root cert? Can you see it under Settings -> System -> Certificates? Also, is it expired or not?

If you can, that means it is installed correctly. Then what you need to do is to figure out what type of 802.1x authentication your network is using and edit that by go into the existing connection's "Network" tab and change it. Don't forget the encryption method too (I would assume it's WPA/2).

Good luck!