If you have gutters on your roof, place your barrel under the down spout so water flows directly onto the top of the barrel.
If you do not have gutters, but have an area on your roof where there is a valley or steady stream of rain off the roof during a rainstorm, simply place your rain barrel so that the rain will stream onto the top of the barrel.
If you have a down spout that goes directly into an existing dry well or draining system, you may want to purchase a rain diverter (sold separately) to funnel the rainwater to the top of the barrel. When the diverter is closed, it connects your down spout back into your drain system during the winter months when you do not want to collect rainwater.
A full rain barrel will weigh around 400 pounds. Place your rain barrels on a surface that is flat and level. A good base can be made of cinder blocks, landscaping blocks, or a sturdy wooden stand.