A block and tackle is a pulley system consisting of a block of upper, fixed pulleys known as sheaves, and a corresponding set of movable pulleys below. The rope running through the block and tackle needs to be fixed at one end and is manipulated at the other. These systems are commonly used to lift heavy objects and require some simple set-up procedures before the actual lifting can commence. Luckily you can easily get the pulleys up and in order, no matter how many sheaves you have in your block.
Hang the block from the location where you want to suspend it. Hang the hook of the block on the suspension area and make sure that the suspension is strong enough to support the load you will be lifting.
Move the object you're lifting so it is directly below the block, and tie the end of the rope to one end of the object. Either knot the rope around a pre-existing handle on the object, or pass the rope around the object itself before knotting it securely.
Pass the rope upward through the first sheave in the block and bring it downward to the object. Put the rope through one of the moving tackles of the pulley so the rope is on the underside of the pulley gear.
Bring the rope up through the next sheave in the block and back down through the next moving tackle. Keep doing this until all the sheaves of the block have been strung. Leave the end of the rope hanging down.
Adjust the tackles until all of them are low enough to mount the object onto. Start with the tackles closest to the tied rope on the object and pull each one down until it is in the correct place.
Pass separate pieces of rope around the object at each point where there is a tackle above it. Feed the ends of each rope through the tackle directly above it and knot it to attach the object securely to the pulleys.
Pull the loose end of the rope to initiate the lifting process and set the pulleys in motion.
You can buy block and tackles with hooks already attached to make mounting them even easier.
Do not use a block and tackle system for lifting humans unless it is specifically graded for that purpose.