Look at the link above. You need to remove the buttonhead screw #183, push the firing pin in slightly and tighten #183 again.
Look at your firing pin it should have a U shaped area that the buttonhead screw fits into. The screw riding in this area is what allow the firing pin to go far enough forward to strike the primer and keep it from coming out the rear of the slide.
When you reassemble put a very small amount of blue loctite on the last few threads (near the head) of the screw. That will keep it from backing out.