I'm not the best critiquer but I will give it a try.
First off you have a chair seat.. you really need to put your stirrups down and bring your leg back and relax put you heals down and sink all the weight into them!
You have pram hands you might want to put thumbs on top =]
I also agree with what has been said above.. That saves me typing some more haha
With your horse, He/She looks heaps tense and not relaxed at all.
Personally you should only walk and once you've got Him/her relaxed heaps in the walk wanting to stretch down, working off your leg, suppling, bending etc etc then ask for trot.. and do what you've trained in the walk but for the trot and when she brings her head down to stretch ask for some more forward and then she'll round her back and drive from behind rather then forward but if she goes to bring her head up don't grab the reins stick your hands down to force her (yes im saying it's a girl lol) just do what you done more .. ask with your leg and seat using the inside rein to ask for her to supple to the inside.. And so on and so on. It wont happen over night that's for sure it took me and my horse 4 weeks to master that.
=] But this is my way of doing things, a lot of people do it different for each horse. So if it works it works if not try doing it another way.