If you're using windows:
1. Press "WIN+R" and type "cmd" in the prompt
2. Type "ipconfig", press enter and find your "Local area connection"
3. Check the "Default Gateway" IP address and type that into your browser
4. Log in to the web-based configuration utility using the method specified in the manual (usually username is "admin" and password is the default wifi password printed on a sticker on the router)
5. Go to "Wireless configuration" etc and dial in the settings you want.