Is it the RCBS type?

If so, loosen the cap on top and push a loaded shell in, "nose first". The jaws under the cap need to catch in the grove that the "rifle's extractor" uses to pull the shell out of the chamber of your rifle.

Once that's in place, tighten the cap back up and use the puller like a hammer, pounding on something solid untill the bullet comes out. You will soon learn how many times to pound it, and how hard, for the bullet to come out.

"If" you have more questions, come on back here and ask them.

Drilling Man