Start by working at the bottom of the dressage training scale: USDF | About | About Dressage | Dressage Training
First you MUST have a steady rhythm
with energy (he can't be "dogging it") and tempo. Since he doesn't seem to care for rein contact (in racing the harder you pull back the faster the horse goes) start with a LONG rein but a steady connection
. I suggest concentrating on the walk and trot until you get those correct. Now I say a long rein but that does NOT mean a floppy rein with no contact. Rather it means that EVERY step he takes you must follow with your arms. When his neck goes (naturally) down your elbows come forward off your waist and follow, at the next step his head/neck will come up and your elbows will come back onto your waist. Thus no matter where his head and neck are (up in air, down towards ground) the rein length and feeling (heaviness/lightness) remain THE SAME!
Next you would work on relaxation
(with elasticity and suppleness). If you did rhythm
correctly and ride it well he will be relaxed. Most OTTBs loose the relaxation at the canter so before you canter with him work on the walk and trot. Make certain you can turn him without his popping the shoulder or holding the bit and refusing to bend.
Take some dressage lessons but do look at the training scale to understand how to get there (Collection is the hardest for the horse) from here. It will take months to get the first 3 (up to connection - which you referred to as getting him into a frame) but if you do it correctly and slowly, allowing his muscles to build up without pushing him so hard he's too sore, you'll be thrilled with the result.