I've been really working on dressage for about a year now, and even though I'm no expert, I figured I could go ahead and discuss some of the basics of the discipline's tests and how I've dealt with them so far.
The first level of dressage competition is called the Introductory level, which starts with tests A and B being walk/trot only, since the canter can be difficult and elusive for beginning riders.
The first movement of Test A begins with entering the arena (at A) in a rising working trot down the centerline. I'm not entirely sure if there is a requirement for a halt and salute at the beginning of the test since its not listed on the paper, but in several videos online a halt is shown. When I've practiced the test however, I have not added in the halt. After X, there is a transition down to a medium walk before reaching C (the end of the arena). One of the biggest requirements for this movement is straightness down the centerline, which is deceivingly very hard! Lady is still learning to actually stay straight and especially in the transition to the walk, we wobble around and lose our straightness. Rhythm is also important, and can also be lost through the transition, but ought to be kept consistently throughout the entire movement. Lady and I can make the transition, but getting into the rhythm of the walk is what throws us off.
Movement 2 has the horse and rider track right once they reach C (the center of the short end of the arena). It is important that they retain balance and have correct bend through the corner. At M is a transition to a rising working trot again and again, the balance of the transition is emphasized. The trot continues along the edge of the arena until the pair reaches A and then begins movement 3.
Movement 3 continues with the rising trot, making a 20 meter circle beginning at A, and using K and F as side points of the circle.
Lady and I are still working on the straightness portion of movement 2, but we've gotten pretty good at the corner bends. The circle in movement 3 jams us up a lot though, because of the geometry. I don't see the shapes very well, which messes Lady up (obviously).
The remainder of the test is as follows...
Change rein across the diagonal (K-X-M)
20 meter circle, tracking left at C, rising trot.
Transition to a medium walk between C and H
Free walk across the diagonal (H-X-F)
Transition to a medium walk between F and A.
Head down the centerline at A
Halt and salute at X
The first three movements is about as far as Lady and I have come on this test as of the last time we went through it. We're working pretty hard on making smooth transitions, balanced turns, and rhythmic gaits. It's coming along swimmingly so far and I'm hoping to move on to test B and possibly C soon.
https://www.youtube.com/watch?v=5FJgBsvARtU - Watch an example of this test!