From the rap rings hopefully situated next to the tree.
You could skip the gear entirely and just drape the rope around the tree, but then on pulling the rope you'll damage the bark, hurt the tree, and I wouldn't do that unless it was an emergency.
You didn't specify the circumstances. Is this an emergency retreat? Something you plan on actually doing or just as a brainteaser? That's a pretty small tree to trust your life to, depending on soil and type of tree it could pull out. Why do you only have 5 feet of rope and not any slings? Do you mean cord? You could also tie a loop around the tree (join ends with double fisherman's knot) and put the rope right through there to get the rope over a lip (since rope won't be moving while weighted it's ok, although when pulling it can damage the cord leaving behind tat that someone else might use and then it fails). Or you could oppose and reverse the biners, leaving behind your entire stash of retreat gear.
I guess, in summary, this isn't a great situation, and without knowing more about the context it isn't possible to give a good answer, all my above rambling is rubbish!