Go to your browser. Type in 192.168.1.1 or 192.168.0.1 and type in the username and password then go to the security tab and there it is. If you can't use wireless then you will have to plug in an ethernet cord to do it. Username is generally blank and the password is admin unless you changed it.
1)Open the web browser that you use: Firefox,Google Chrome,IE,or Opera and type in the IP address for your router,and press the Enter key. http://www.routeripaddress.com/< Router ip addresses can be found here
2)A window will open and then type in your routers default username and password,and press the Enter key again http://www.routerpasswords.com/< Router usernames and passwords found here ***** Username and Password may also be located on the side or bottom of your router *****
3)Navigate to the Wireless Security\Network Security Settings Tab and open to locate or change your WEP or WPA Security Passphrase. Use WPA because it provides better security.
4)Write this Security Passphrase down and put it in a safe place to access when needed.
^^^ Yeah, they are. You'll of course need to know your user's keychain password, and if the Keychain Access utility had the right password, and the user's login automatically included keychain access, OP wouldn't have a password related problem logging on.
To find the Keychain Access Utility:
Applications -> Utilites -> Keychain Access