"The procedure is simple, and the only materials you need are a regular-size blanket and — in most situations — about 24 feet of rope. The exact length of rope required will, of course, depend on the distance between the points from which you’re going to hang the hammock… As for the blanket, its width will determine the length of the finished hammock, so the only problem I’ve encountered in making an adult’s hammock is finding a blanket that’s wide enough.
Once you’ve selected a place to hang the hammock, double your rope end to end and tie it in place so that the twin cables droop in a gentle curve. Now fold a short side of the cover over one of the ropes so that a little more than a fourth-but less than a third-of the blanket is hanging between the ropes. Pull the rest of the blanket under both ropes and fold the other side over the second rope, toward the center. The two ends of the blanket should overlap each other by at least several inches. That’s all there is to it. When you lie in the hammock, your own weight on top of the blanket’s overlapped ends keeps the whole thing from slipping apart and dumping you on the ground. Surprisingly enough, the arrangement is completely sturdy."
You can also check out a diagram of the method over here to help clear things up a bit. If you get one rigged up, don't forget to send us a picture, that is, unless you're too busy catching a cat nap in the sun!