You have to use your imagination a little because it's not exactly the hitch to the tree.
But the idea is dead simple. Put a carbiner on your rope a couple of feet away from the carbiner at the ends of your tree huggers (or webbing). You can "clip" the carbiner onto the rope simply, with a lark's head. Now you put the working end of the rope through the huggers' carbiner, and bring back to the biner you put on the rope, loop it through that, and bring the rope back to the webbing. You can tighten the rope, enjoying mechanical advantage, and tie it off.