You do not want to put a shed down on a non-level area for reasons too numerous to list. You could make a perimeter wall on the downside out of large rocks, or pressure-treated timbers held in place with rebar pounded into the ground through holes drilled through them. Then you could lay in gravel and level it out to have a decent surface for the shed.

Adding a perimeter wall on the downside of the sloping ground will really help to level it out. Foundation is the greatest factor in making any structure and where most of the effort should be focused on. That makes sense kudzu9. Thank you.

There are so many options/possibilities...hope you ended up with something that will endure....:)