Where do I stick it? My current set up is in a slight alcove meaning that bass tends to be quite powerful in the mix. I'm not sure if I stick it behind my monitors or on the wall infront of me or behind me etc?
General rule for acoustic treatment; treat the corners of the room first thing with bass traps, then treat early reflection points on the left and right walls (usually left and right of listener) then diffusion points on the front and rear walls and also have a cloud over head to treat more reflections off the ceiling.
If you're primarily trying to treat the bass, foam won't do much unfortunately. Foam is really only good for mid and high frequencies. Bass travels straight to the corners of a room so some 4" thick bass traps in each corner will reduce the resonance of the bass in the room.
Oh, if you haven't got some monitor isolation pads, i would start there first. MoPads are very decent and will make a huge difference to bass response.