I am an older person who grew up with The Apple, RadioShack, etc. computers, and the newer computers baffle me. This is a very basic question, but how does a home network or a wireless system work? My house is wired for cable and Internet service, I have an outlet for them in every room. The system is in the laudry room, where I have a Cable Modem feeding a 4 port, wireless router. I can select which room to use for Internet by plugging in a cable from the router to the choosen room outlet. I have three computers, #1 and #2 are towers, and #3 is a laptop. The laptop is wireless, the towers are wired.
Can anybody explain how to tie all these computers together so that I can use the printer that is connected to Computer #1 from the other two computers? Or how I can access the files in any of them by the others?
Also, would it be better (and easier) if I get a new, wireless printer? How would that work in my setup?
Any help is appreciated.
BTW I am running XP on #1 and 2, and 7 on the laptop
Can anybody explain how to tie all these computers together so that I can use the printer that is connected to Computer #1 from the other two computers? Or how I can access the files in any of them by the others?
Also, would it be better (and easier) if I get a new, wireless printer? How would that work in my setup?
Any help is appreciated.

BTW I am running XP on #1 and 2, and 7 on the laptop