On the router configeration page - fire up your web browser and type in your ip address (usually on the bottom of the router) e.g 192.168.3.4 and you should come to your router configeration page. Go to the security section and you should be able to enter a WEP key (usually 11 charecters long). This can then be entered into all of the pcs for them to comunicate securley. You may alternitavly be able to set a password which can then be entered into the pcs with the software that came with your Wi-Fi card. The advantage of this is it is easier to remember if you ever need to add/rekey a pc. However the disadvantage is that some software requires that you enter it in every time you turn the pc on.