There are a few different types of solar stills that you can use. The basic principles are that you dig a hole 18 inches deep and about 3 feet wide. Put a collection bottle or cup in the center to collect the water. Here is where some of the difference come in. For a still without adding additional water, cover the opening of the hole with a clear sheet of plastic.
You can use rocks to hold it down. Make sure that the plastic forms a cone down inside the hole, so when the condensation happens it will fall into the cup. This type of still should gather 1 pint of water or a 24 hour period.
You can add a length of hose to the inside of the still so you can just sip up the water that is collected.
In the center of the original hole we put another hole the size of a soda can about 2/3 deep. Then placed the plastic garbage bag over the bottom with a hole in the bag for the can to stick through, then we put sand on the bag.
Dirty water went on top of the sand. A plastic bag goes over the top like the original, in the shape of a cone secured with rocks around the edges.