How to make a WAN connection 'secure'?

using ptcl broadband, connected the LAN wire of shiro modem with zyxel wireless router P-320Wv2 WAN port. ok its working fine, but i now want to make it secure by adding a 'key'. how can i do this?

Go to the router setup and poke around. Its probably at this ip:

yes sah i've read the manual (very un pakistani : ) but the address they have given opens up shiro page! so i cant move forward.

Disconnect your Shiro modem from the router, and then try again. Apparently both your modem and router are configured at, so there is an ip conflict. The router setup will probably also allow you to change this IP to avoid future conflicts.