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/92/d-link_routers/< 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
3)Navigate to the Wireless Security\Network Security Settings Tab and open it to locate your WEP or WPA Security Passphrase.< Change it here in the Security Settings Use WPA because it provides better security.
4)Write this Security Passphrase down and put it in a safe place to access when needed.