Type this into your web browser: https://192.168.1.1
It will bring you to the Linksys setup page.
A window will pop up prompting you for a username and password to access the configuration page for your router. Enter "admin" (without quotes) for both the username and password.
From there you can change your router name if you feel like it.
Click on the Wireless tab at the top of the settings screen. Change the Wireless Network Name (SSID) from the default value to something unique (you can use the same name you set as your Router Name in the previous step. Then Disable the Wireless SSID Broadcast option and click Save Settings.
Now click on the Wireless Security subsection at the top of the page. In order to password protect your wireless network first use the Security Mode dropdown box to select WEP and then from the WEP Security dropdown box select 128 bits 26 hex digits. Choose a password between 6 and 8 characters and type it into the Passphrase box. Then click Generate. Finally click Save Settings.