Depending on if it's an open show, or a specific breed show, your jog may be different, and the way the horses head should be may be different as well.
I rode a walk jog class last month with a QH, but it was in a open show. In AQHA shows the jog needs to be slow moving, effortless, and with the horses head and neck toward the ground.
In my open show, the judge is looking for a faster jog (but not a trot), with the horses neck flat, straight, and head on it's vertical. Make sure the horse is coming from behind, and not pulling forward with the front.
In equitation, it is to be ridden with one hand. Yet, you need to hold your other hand up with the one holding the reins, as if you are riding two handed.
Good luck! Hope this made sense?