how to connect a laptop to someone else wireless router...

You don't need "router software" on your laptop. Why is it there? (Side question - irrelevant to your question).

You need to enable your wireless adapter on your laptop and then it MIGHT connect on its own (if your g/f's router has no security encryption).

If it has security encryption, you will need to open the wireless utility and enter the encryption key.

Ask your girlfriend. You'll need to get the details about the wireless setup on the router. If nobody's done wireless setup on the router, then that's a security hole that should be fixed by someone who knows or can learn the difference between WEP and WPA, etc.