mac-filtering wifi router

enter the configuration of your router by entering its ip-address in the addressbar of your browser.

if you don't know the ip-address of your router, perform the following steps:
-connect to your router
-open a command shell (all programms -> accessories)
-type the command "ipconfig" and press enter
-search the output for your wlan connection and lookup the address of the default gateway
-that's the ip-address of your router

now you can enter the router configuration with your credentials.
in the configuration look for mac-filtering and enter those mac-addresses which should be allowed to use your wifi.

if you want to find out a mac-address of a windows 7 pc follow this link:
http://uklaninfo.rrz.uni-koeln.de/info/macwin7.html