If you are trying to set up a security key for a wireless network then take a look at the link below.http://windows.microsoft.com/en-US/windows-vista/Set-up-a-security-key-for-a-wireless-network
If you are trying to recover your security Key then follow the steps below:
1. On your Home PC, that connects to your Wi-Fi Network, click on the Wi-Fi Network Icon on the taskbar.
2. Right-click on your wireless network connection and click “Properties”.
3. In the Wireless Network Properties, click on “Security” tab. You can see the Network Security Key that you entered during setup of Wi-Fi Network. But by default, it will not be in readable format.
4. To make the password readable, check the box “Show Characters” and voila your Network Key is readable!
I hope this helps!
Windows Outreach Team