Personally, what I think you should do is study information on horse striding, learn your horses stride length and practice 'jumping' ground poles. Practice your own 'jumping' skills. Make trotting poles or just set poles up around the ring like as if it were a jump course. This will help teach you how to measure the horse's stride, without having the danger of a full jump. In this you can master the basics of the skill and save the more dangerous aspects of the sport for when your trainer is around.
Do you know a proper half seat? Do you know how to shorten and lengthen your horse's stride? Sorry to ask thing if they're simple easy things for you, but I don't know you nor your riding level. If you can set up your camera or phone camera in the corner of the arena where you can see most of the arena, and ride your 'jump' course, then review you tape, critique your own body position and how well you prepared your horse for each ground pole.
Once you have your trainer with you she/he can better help you with what to look for in your videos and can give you in person tips, then she/he can decide when you're safely ready to move up to real jumps.
You can also post your videos here for a critique :) Sometimes it's fun to have lots of eyes on board!