your question is a little confusing. So are you saying that you have a desktop computer and a laptop computer and want both to talk to each other? Assuming you are running win xp. Make sure that the firewall is not turn on, on both system. To do so, click on start - control panel -firewall and turn that off.
Also at the control panel
click on tools (menu bar) - folder options - view tab. Scroll all the way down and uncheck, use simple file sharing.
As far as securing your wireless. You can enable WEP, WPA, or other secure wireless. You can also do the MAC identification.
to get your mac id, click on start - click run - type cmd. at the command prompt type ipconfig /all press enter. The mac address is the physical address of your wireless card. There can also be address of your network card as well, ignore that for now.
hope this helps.