help!

I've seen Hellraiser a long, long time ago and I liked it. I've seen Hellraiser 2 a long, long time ago and I liked it. I also saw Hellraiser 3 a long, long time ago . . . But when I saw Hellraiser Bloodline . . . I never watched the Hellraiser movies again until recently when I came across Hellraiser Hellseeker and I figured I would give the other Hellraiser movies (the ones I didn't see yet)a chance. Can somebody please tell me what the hell is going on???? What is the deal with this puzzle box and who was Pinhead before he became "Pinhead"-From Hellraiser 3 (of what I can remember) he was a soldier? Can somebody explain the whole deal with the puzzle box, who Pinhead was, who he is now (with pins in his face-the leader of hell?)and what happens to ppl who open up the puzzle box?????

thanks
(I'm going to post this ? on other hellraiser boards so I can get the best explained answer)