If it's HWH like ours, you turn it on and it will show you which side is low with a little amber light. You lower that jack or jacks until the little light goes out. Sometimes you need to raise the front or maybe one side or the other.
I usually try to extend all the jacks to ground contact to hold the coach stable when walking around.
Be careful if you raise the driver wheels off the ground as then the coach can roll off the jacks. To do that you need to chock the wheels.
To retract all you do is turn the system on and select the "Store" button. They will retract and when done the light will go out. The coach will not air up until that light is out. That's if you have air ride.
Jim and Carol Cooper with Oreo the Kitty
FAA ATC ret, VFW, Legion, VVA, NRA
2002 Journey, Cat 330, 2015 Ford Explorer Blue Ox, AF1