how to do switch the wires inside the phone jack to a second installed telephone line?

GO TO THE PHONE JACK THAT YOU WANT YOUR COMPUTER HOOKED TO, TAKE OFF THE FACE PLATE AND PULL THE JACK OUT. THERE SHOULD BE TWO WIRES NOT INUSE UNHOOK THE RED AND GREEN WIRES THEN HOOK UP THE YELLOW AND BLACK WIRES. YOU CAN ALSO BUY A DOUBLE PHONE JACK WHERE TOU CAN HAVE BOTH LINES HOOKED UP AT THE SAME OUTLET.HOPE THAT HELPS.