First of all you need to understand that being framed comes frames hindquarters and posterior limbs.
To be able to be framed, your horse needs to be reactive to your legs, this is the most important point to step under in order to raise his back to finally yield his neck.
For a young horse, you can make him used to work on the right way by being lunged with lunging system (this way he won't have the weight of the rider and the parasite movements of the hands) to make him find his place by his own.
Then, you need to start you session in full extension of the neck to stretch his back.
My tips for a young horse are:
Put your inner leg at the girth and push with it to the outside rein that is tight, play with your interior hand to make your horse relax (without moving the wrist), you can open your hands in funnel and when the horse goes down you put your hands back at the wither.
Make a lot of work on circles, flexion will soften your horse but the most important is to never let go of the contact with the horse's mouth.
I hope i could hep you, good luck, it is a work of patience and time :)