Network to connect to the Internet

I possess three computers, on all Windows 98 is loaded and I have only one telephone line dedicated for the Internet. Each Computer is found in three different rooms. I want to have Internet access on all the three computers. Can anyone explain to me in details how I may proceed. Situations may exist that all the three computers may be surfing at different sites at the same time.
I have been told that I may use a sharing modem for that purpose, others advise me to build a small networt with a network card installed on each PC. What is the best way to do it? and How to do it?