I'm not sure you are understanding. (And I don't know how flash drives have anything to do with this post either...) If both computers are connected to a router with the same workgroup name, they are in the same network.
So maybe i misunderstood you. Is the computer you are sending things to in your house, or is it your friend that you are sending stuff to. If it is your friend, networks have nothing to do with this...tell me if its your friend that you want to send things to...
But, if i understood you right, you are trying to send things to another computer in your house. For this to work, you need both computers connected through a router, or directly with a crossover cable.
I'll assume you have a router. And, Ill also assume you are using windows XP, once again, TELL ME IF YOU HAVE WINDOWS 98 OR ANOTHER OPERATING SYSTEM OTHER THAN XP. Do what I mentioned before and set up file sharing. Then, as i also said, right click on My Computer and go to the computer name tab. Go to change, and change the work group name to the same thing on both computers.
After this, go to MY NETWORK PLACES on your XP machines, then go to "Workgroup Computers" to the left. Or, you can type //yourname (Yourname being whatever WORKGROUP name that you used) and it will take you to a list of all computers connected.
Something about your question seems odd though, it seems like we aren't on the same page here....
If none of this answered your question then reword it and ill be happy to help.