Go to your menu bar and click on the airport menu item producing this menu, select "WSU Wireless".

This should result in it asking for your credentials (same as my.wsu.edu).

Which results in this (Don't click accept yet -- click show details for the pane after this):

Then it will ask you to accept the cert ( check the box, that way if it ever changes you will know -- it will change once in the future because it is currently a self signed wsu cert, but other than that if the cert changes thats BAD ).

You should now be online, you can check by going to the network section of system preferences ( easiest way is to go to the bottom item on the airport menu "Open Network Preferences..." )

At some point it will ask you to allow the wpa client access to your keychain either durring the above or upon the next connect, select "Always Allow" unless you feel otherwise inclined.