You might get a better response by posting this thread in the Networking forum!
If I understand you correctly your set up should allow you to Network in the way you want. You'll need to make sure the Desktop and Laptop are connected to the same Network - i.e they are on the same named network. Run the Network wizard on your desktop and note the exact names you enter, then select 'make disk' option at the end and place the disk (could be a USB Stick) in the Laptop and run the file created by the Desktop. You will have needed to select File/Printer Sharing when you first ran the Wizard.
If you go 'Show all connections' and right click on the LAN card you can select 'Properties' - this tells you the protocols you have active (Client for MS Networking, File/Printer Sharing, TCP/IP).
Finally check which files you have set for 'sharing'. Never share a whole drive on a WiFi network!