What is the easiest way to level a 8'x20' area so I can place a storage shed there??

If you have the resources, have someone with a Bobcat (Earth moving Equipment, Bobcat dealers - Bobcat Atlantic) come in and level the area. It might take them a couple of hours including unloading and loading the thing. If you don't have the resources, it's pick and shovel time.

On thing to remember either way is that "leveling" isn't exactly what you are looking for. You want to put your shed on level earth that hasn't been moved. You don't want half the shed on unmoved ground and the rest on filled. You want to work the area so you can have a solid foundation all around. Otherwise, when the filled area settles, your shed can have some problems. This might mean that the area you want leveled is larger than the dimensions you stated.

Good luck.

Depending on the slope I'd drop about 3 yds. Of limestone screening and level with a rake.