You should be able to get to your passwords if you are the admin.
"I set up my WPA2 network and checked the box to show the password and still when I go into AirPort I can't select the box."
Did you restart your computer afterwards?
Suggest that you cross-post in the AirPort where the AP users hang out if you are having problems.
Open Keychain Access.
Make sure that the lock in the upper left hand corner is unlocked.
In the upper column at the left click "login"
In the lower column at the left click "passwords"
Find the name of the network and double click it.
Click and check off the box at the bottom of the new window that says "Show password:"
Enter your administrator password.