pulling back?

So my gleding has started to pull back and has struggled and pulled his lead rope free in a rope halter. He will try to get away from anything I would love to get him more willing he's usually a good boy but he likes to pull back I have him in a rope halter anytime I work with him he's just fine saddling and putting on boots without tied up but for trails, and show I need him to be tied!

Any advise?

A couple years ago when I was doing a course in breaking in, we had to teach our horses to tie.

How we did this was to place a towel up around their necks and tie the ends together, thread the rope through the halter, and then tie the horse. Basically what it does is when the horse pulls back, a little pressure is put on by the halter, but the majority of it is put through to the towel. Our horses learned pretty quickly that they can't get away, and it also taught them to give to pressure. I don't know if this will work for your horse, but it might be worth a try. Make sure you have a good quality rope though and tie them to something solid (with a quick release knot of course, in case something goes wrong). My past mare pulled back once when I had her tied to a gate. She bent the gate and snapped the clip on her lead rope.

How long should the towel be, he has a large head..?

There are devices such as The Clip that teaches horses not to pull back, it gives and allows the horse to pull, but not get away or break ropes and halters.