Here are a few pictures that might help. The cables all route across the top tube: rear brake on riders left, rear derailleur center, and front derailleur riders right.
The cable for the FD comes down from the top, cable jacket into top of derailleur, cable continues through it and is anchored by a small bolt behind the bottom bracket (into the frame).
The front brake cable goes through the stem: the jacket bottoms out into the inside bottom of the stem, cable continues through it to the brake.