For millennia, pulleys have been one of the basic machines used to make work easier. The Greek mathematician Archimedes designed one of the first known block-and-tackle devices that used a rope on a pulley to lift items that were impossible to lift by hand. Threading a pulley is one of the crucial steps to keeping the machine in order — and avoiding dangerous accidents.
Attach the pulley to a secure place. This could be a joist in a roof, in which you've screwed a hook, for example. The size of the hook and the steps to secure it will depend on the load you're lifting.
Run your rope over the top of the first pulley after you've attached that pulley securely. Make sure the rope sits in the pulley channel so that it won't slide up or out as you're lifting.
Let the pulley rope go down and attach the rope to the item you want to lift. You could tie the rope around the object or tie it around a hook or other accessible piece centered on the weight. Now you are ready to lift.