New iMac 7.1 trying to send a fax

I recently upgraded from an eMac, and today when I went to send a fax I found that the phone line I used to use did not fit into the only port where it would go (the ethernet port). I am probably missing something simple, but can someone advise me how to send a fax on this new unit? I know technically how to do this but not physically, do I use a different type of connection between my phone jack and the computer?
Thanks in advance for your help.
Cindy D