I do live in a urban-ish area so trees that I can use for branches do not belong to me. For visual instructions (photos) i will be using drawn pictures of actual photos. i did make this once at a camp. I was going to take pictures of my wonder creation but i sadly left my camera at home. again.
Step 1: Getting the legs
Get 3-4 big rocks and having them about the same size. Get the 2 biggest ones and put them so you can fit in the between them. So you head should touch one and your feet should touch another. Now move them in about a foot each so on rock should be where your head is and the other should be where you ankle is. If you have 3 rocks, put the last one in the middle. If you have four put, them evenly in the middle. This should help the frame hold your weight. The more rocks the better.
You may not find rocks with flat tops. Find the flatest ones and put dirt on the top and even it out. In addition to level surface, it also gives a bit of bounce :)
If you can't find rocks in general, a mound of dirt works just as well.