Laptop 2 PC with wireless router

Components:
1 wireless laptop
1 PC
1 Belkin ADSL modem with built in wireless router

At present the PC and Wireless laptop both connect to the internet ok using the wireless router. What i want to do now is allow the laptop and computer to share files etc. I have been trying to do this using the windows wizards, network places etc. I haven’t had any luck. How do i get them to share files???