If you are talking about a regular RV cover, then set it up on the ground by laying it out with the all the zippers and straps showing. Start folding each side of the cover along the long side in towards the middle of the cover (about 2-3 feet for each fold). When you reach the middle of the cover for each folded side, fold one side over the other. Now, fold each end toward the middle (again 2-3 feet for each fold). When you finish, you should have a bundle all folded to the middle.
To put the cover on your RV, carry it to the roof and place it in the middle of the roof (Remember which end of the cover is on top and point it in the right directions. Having to turn it around after unfolding is a royal pain.) Unfold the cover to the back and front of the RV, then unfold to each side and drop it over the side (Check to make sure the zippers end up on the entry door side)
Finish tying down the cover and you are done. Tie the cover down well so it will not flop around in the wind and wear on the RV.
An additional suggestion, if you live in a climate with significant rain or snow, go to your local Dollar Tree or equivalent store and purchase 3 or 4 cheap laundry baskets (the rectangular type). As you are preparing to put the cover on, lay the laundry baskets wrong side up and length wise down the RV.
This will give you a tent effect to allow the rain and snow to drain off the roof and keep the cover fairly clean.
Trying to put the cover on from the ground is a major effort and a real pain in the rear. (I learned this from experience.) If your start from the roof of the RV, it will go alot easier.
Ed & Michele :C