How to password a wifi

Hey! I recently pressed the padlock button on my router accidentally. It has took the password off my wifi connection =/ and I dont know how to get it back on. Im using a G4 Powermac & a macbook on wifi.
Any help here would be appreciated.
It is a TP LINK WR841ND if that makes any difference?!

 

Hiya,

you need to get inside the router
Plug in an Ethernet cable to your router and your computer

look on the back of your router for the default login and IP number
your'll need to enter the IP number in your browser, this should open the web page for your browser and allow you to login using the default login and password

then you will most likely have to choose wireless set-up to change the relevant settings