Try to access your router's gui. To do this, you have to use your internet explorer.
1. Get your default gateway address first.
a. press the windows key + R
b. type cmd then press ok
c. on the black screen type ipconfig then press enter
d. look for the default gateway address
2. Type the default gateway address on the internet explorer address bar and you will be able to see your router's gui
3. Refer to the manual posted on the link below. Refer to Chapter 7 to get the WEP key of your router.
note: you need to connect wired to your router before anything else.
Netopia Wireless Router Manual