If both computers are connected to the router it's fairly simple to set up a network -- though personally I would establish the links with ethernet cable first and then use wireless once it's all working.
1) set file sharing on relevant folders.
2) Note down names of both computers (Control Panel, System, Computer Name) 3) Turn off firewalls on both machines.
4) Got to Control Panel, Networking and select Network Wizard.
5) In My Network Places select Add New Network Place.