How to use a puller
First remove any retaining bolts on the pulley, then position the tool so that the 3 ( typical ) arms are hooked behind the pulley and screw the center down to the bolt until snug.
Then using a wrench turn the bolt in the center of the puller, as you do the pulley will slide out with it. It might help to spray the shaft with penetrating fluid before attaching the puller.
Go slowly, too much pressure may break or bend the pulley and the puller may pop off several times before you get it right.
It is important that the arms of the puller be equally spaced and centered on the pulley for correct removal.
You may need to change the positioning of the arms in order to reach behind the pulley, most pullers have two sides each with near and far holes for the bolts.
Pick the adjustment that best fits and leaves enough room to tighten the center bolt for removal.
The center bolt must be centered on the shaft, if there is no taper or bolt hole in it use a center punch to make one so the puller stays centered, without a guide the puller will try to walk off the shaft as you turn it.