I doubt if anyone could answer that question unless they were there looking at your computer.If your using Microsoft it should have help files for you to go by.
do you have a router and is it connected and/or is it wireless? what are the specs of your 2 pcs?
create a topic in the appropriate forum & be more descriptive
Well, IF you are running Windows 7, which we dont know, go to the control panel, then navigate to Network and Internet, Then navigate to Homegroup and create a new homegroup which will then supply you with a Homegroup logon Password that youll need for the other computer to join, which is much easier to have windows 7 as well on the other computer.