Then, you drape the affected leg (the leg that is on top, not the leg you're lying on) behind you, such that your foot ends up below the level of the bed.
You're basically stretching your hip farther than you could stretch it normally, since you can drape it backwards into empty space.
Play with it a bit, with different angles, etc. This is the stretch that can have you go from debilitating pain (I couldn't even walk properly) to completely asymptomatic.
This is a good stretch for everyone, since even if you don't have "IT band issues", most people have much tighter hip joints than they think, and it affects the health of your knees and back.
Image here: http://www.runnersworld.com/sites/default/files/rt/images/20...
Regarding form, I would say it's not something you need to focus on. Do try to run as straight up as you can, like you're a marionette suspended from strings with your legs moving beneath you (probably same thing said another way as "pretend you're running on thin ice"). But other than that your body will mostly sort form issues out unconsciously as you very slowly ramp up running mileage.