What TheChas said is quite correct, but there are some other little problems. The user on the machine has to have power user rights so that he can share the printer. Then, you go to the Printers tab, rightclick the printer, Sharing and check the "Share as" buton, write down a share name and then press ok.
From the other computers, go to the My Network Places, browse till the computer that has the shared printer, expand it and then doubleclick on the shared printer and press YES when asked to install the printer.That's it. Good luck!