Sorry, this isn't really a step-by-step how to. If that's what you're looking for check out this Instructable. The Instructable has a two ply hammock. We did just one ply.
Cora found the perfect nylon material at Walmart, and it was only $1 per yard! Her material was 45" wide and 3 yards long. She serged the two raw edges and left the selvedge edge intact. Then she turned and stitched, making a simple 1/4" rolled hem, down each long edge (the selvedge edge). On the serged edges, the short ends, she turned and made a 1" casing. Through the casing she strung some rope, pulled it tight and viola: hammock done.
Afton found her fabric in my fabric stash. The pink ripstop wasn't quite long enough so she decided to do a color block with the pink in the middle and some grey plaid nylon on each end. Her project took longer because I made her do flat felled seams on the blocks so it would be strong enough to support the weight of whoever used it. She caught on to the flat fell pretty quick and finished her edges and ends the same as her sister had.