The knot to tie the hemp to the flat is a bowline.
The knot to tie the hemp to the bar is a round turn and two half hitches.

When tieing flats to bars it can be useful to have a couple of people in steelies foot the flat since the hemp stretches a bit under tension.

It will take you multiple attempts to hang the door.
Check the door you're using fits the door frame you're using before you start.
The hinges should be positioned so that the pins of the hinges are outside of the frame.
Prop the free swinging edge of the door up on 2-3 bits of hardboard whilst hanging it so that the door doesn't catch on the floor.