Human shampoo can dry out your horse's skin. Riding a horse requires the horse and rider to work together in tandem. If you are a newcomer to horses, we suggest you take some riding lessons. You will need to learn the movements and pressures that are the universal language between horse and rider. Horse need regular exercise and bonding with their owners.
Lack of exercise can lead to health and handling problems.
If you are able, your horse should be exercised once per day or, at least, once per week. This does not mean at a full gallop. Especially if you do not ride frequently. Horses, like people, need to build their stamina and need to have a warm-up period. It is also equally important to have a cool-down period.