first's first's i am a rock climber and also a abseiler and i would recommend getting a proper climbing harness and some rope some caribeaners and a rappel device it will cost a little more but you are much safer plus every piece is tested all you would need is a
1climbing harness (sit harness or full body)
1 climbing rope about for a 10 yard tree you will need 20 yards of rope
some thing very secure to tie the rope to at the bottom (you will proboble have to put it there i recommmend a sport climbing ancor in no less than right up to the hook partwith a climbing adhesive holding it in)
1 repel device (figure 8)
1auto belay (i recommend petzlshunt)

what you will need is to put an ancor at the bottom of the tree tie the rope to it then over a strong branch (put an ancor up there to if you can) with the rope over the branch and on the ground tie yourself into the rope and using knots climb up the rope