How nto give a router internet connection?

Dont pay for internet ';USB Network Adapter'; pick up Neibors ----------OK i turned my first PC to a host com use the ethernet to plug my other pc ACTING AS A MODEN IT SHARES INTERNET SIGNAL ';WORKS'; MY QUESTION IS INSTEAD OF FEEDING MY 2 PC CAN THAT LINE FEED A WIRELESS ROUTER LINKSYS WRT54G TO SHARE WITH MORE