harry, the method you're thinking about now , - in argus's post and the link in rahulrulez's post , it's a bit complex
The easiest way - Your modem should have a built in dialer. Post which modem you have and I'll tell you what to do.
Basically, once you've configured your modem to auto dial, just connect it to your switch, and all the other PC's to your switch, and you will have net