First of all use a lineman's belt with your safety harness. If you are not sure what a lineman's belt is then look it up. If you don't have one, buy one!!! It makes the job soooo much easier and safer. A lineman's belt wraps aroung the tree so you can work with both hands safely.

Set up your climbing sticks, or screw in tree steps,(with your harness/linemans belt on so you can work with both hands).
Screw in another tree step or an eye hook. Use this with a piece of rope to pull the hang on stand up and then tie it off so you can get the strap(s) around the tree.
For safety sake, use the eyehook everytime you climb up, you should have a carabiner on the end of your safety harness. This gives you an extra level of security.
Once your stand is hung, put another eyehook above where you sit so you can hook up when you are on stand. While you are at it, screw in a tree step or bow/gun hanger for your hunting tool of choice and for your backpack and other gear.

The stand needs to in the "folded" position, keeping the straps tight, but not too tight. ( I use a zip tie to hold it until I have the strap around the tree) When you lower the platform it will bite into the tree which will tighten it up. If the platform will not level out then lift it back up and loosen the strap just a little. I also use a ratchet strap as insurance, I don't like the idea of just one strap holding myself up at 20' above the ground.

Try working with it at ground level until you are comfortable with it, no sense learning at 20' up in the air.

I hope this helps you out. Once you get the hang of it it really is not too difficult.

Good Hunting,
Bowflex