I have to agree with the masters, but if you don't have room for the pulley set up, get a hardwood 2x4' or 2x6, and drill 1/2" peg holes every 1" down to at least 30". Use a hard wood peg1/2" and sanded to fit somewhat snug, but loose. Draw your string with both hands, or a draw loop centered on your projected Nock point, more or less. I used a 2x6 piece of redwood, drilled every 2" and marked every inch, worked more or less! Finally got the tiller done at MOJAM on a tree that was setup for pulley! Use what is best for your circumstances. Btw, I'm a newbie and still finding my way!
Hawkdancer