2 Line Filter For SBC with wireless modem

I have 2 desktops in my basement which I want to set up with my wireless router.  I have a 2 line phone.  I have set up the network; however, SBC sent me a single line filter so I cannot accesss my second line right now.  I went to Radio Shack and bought a 2 line filter; however I do not know how to set it up.  The single line filter has a place to put in the phone line and another one for  the connection for the wireless modem.  The 2 line filter does not have a connection to run to the wireless modem.

I cannot use my second phone line.

Suggestions?