Wireless networking help

Okay, Right now I have a home wireless network set up using a Netgear router. I am trying to be able to access my desktop from my laptop(desktop is vista basic, laptop is vista premium) so I can access files without cramming my laptop full of data.

There was a time when I could set Kaspersky firewall to “allow” and it would let me use the files i set to public, but now for a reason I do not know I can’t access it. I get the mesage saying windows is unable to connect, click to diagnose, etc.

So my question is, how do I set it up so I can access my desktop throughout the network from my laptop, without using a direct cable plug in?