New to max, try to understand how the program works using MAX 6 demo, but I see no way to take and pass data from Cubase to a single fader in MAX

I made a simple fader in MAX to send midi data to a fader in Cubase through LoopMIDI, and it works using ctlout but what i need to do so when i move the fader in cubase, max reflect this change?....I tried ctlin, midiin etc with no success, sure i use the wrong syntax or object. Any help appreciated.