Set up poles in the arena down each long side 8m from each short side that will provide a set of four halt over pole obstacles.

Ride around the arena halting over each pole.  After each pole develop a feel of riding your horse ‘up’ through his body and pay closer attention to straightness from nose to tail until the halfway point between the poles then keeping that ‘up forward’ feeling gradually ride up on reducing length steps to the halt over the next pole.  

As you build on this maybe put a trot or canter circle in at B and/or E.

Have fun and enjoy the journey.