This is the quickest and easiest way I know how to hang a hammock between two trees. You will need two lengths of rope and two 3-inch s-hooks, I like to use the 8mm climbing rope and stainless steel s-hooks but you can use any good quality braided nylon rope and zinc-plated s-hooks from your local hardware store.
Take your rope and fold it in half down the middle, now you have the lopped end in your hand and the two ends dangling. Pass the looped end around the tree trunk and then pass the two dangling ends through the loop, pull the rope tight and cinch around the tree trunk.
Tie a knot between the two ropes and drop the 3-inch s-hook behind the knot. Now all that remains is to hang the hammock from the s-hook and do the same on the other tree.
It is important that you check your trees to make sure they are strong, sturdy, and healthy enough the support the weight going in the hammock.
Relax and enjoy your hammock.