First time using amp modeling/DAW help with levels

I've been out of the game for fifteen years, just decided to get back into it. I picked up a guitar, a focusrite scarlet solo, and amplitube five.

between the three knobs on the scarlet, the input and master controls in the DAW in amplitube, the amp head volume, and the volume of my yamaha monitors, I don't even know where to begin. I'm used to just plugging into an amp and playing so I'm lost!