well read the guides on how to attach it to your body, and if its like the harness I use, the find some sort of ring and hook it to the stand's straps some how then attach your harness to the ring.

I have a big ring type thing that is about 1/4 of a inch thick that is hooked to a strap that goes around the tree and is screwed in tightly, and then I have my harness that has a another ring thing on it and i just connect them.