It's all about subtle movements of the body. Like spyder and anabel said it's not trick riding, you can't tug on a the left rein and kick with your right foot and get a horse to do a movement. You have to build up to it.
But when both horse and rider are capable of doing those movements, the aids are generally rein pressure, seat position, and leg cues along with various others. No horse is ever the same, so there really is not "set" way to ask. Of course we all learn the same way but we have to adjust things according to the horse. It's not something you can explain, it's a long learning process with hundreds of vital steps. Miss a step and you won't understand the next.
In the early days of the Indian Territory, there were no such things as birth certificates. You being there was certificate enough. -Will rogers