The manual usually has a quick start guide or something like that.
- Look for the option to disable SSID broadcast (a bit like being ex-directory but not quite!)
- Enable WEP/WPA encryption
- Use Mac Address Filtering (you'll need to find out the Mac address of your (wireless) network card. To do this, go to a command prompt and type:
look for the Mac address next to your wireless card.
Having said that - the manual that came with your kit is the best bet.