RE: safety harness?
The strap you have at the top is for use as a lineman strap. You sling that around the tree and attach both ends at your hips. This allows you to lean back and keep your hands free to hang your stand. There should be another strap with a buckle with a round knurled roller in it that you attach to the tree and clip your ring to that after you climb the tree. Hopes this helps.