Connecting two computers through wireless router

I want to move files from my desktop to my Laptop computer. I have been using my flash card to copy from one and download to the other. I was told that I can connect the two computers together through my wireless router. I have tried this through Map Network Drive but can't get passed the user name and password. Not sure what it is asking for. I tried every user name and password I know with no luck. Can you tell me what is needed for a user name and password. The user name that keeps coming up is the name of my computer\Guest. Example (acer-123456\guest) None of my passwords will work. I am using Windows XP. Help