graphics problem

hi i have a graphics problem
i made a game, with a guy you have to shoot down. The guy is drawen in a picturebox. The annoying thing is for his head for example, i got a circle and outside it a square, which is the picbox. How can i only show the head with the picturebox around it? I have tried using Bitblt, but im not familiar with it and it doesnt work. Please help.
fasa

ok i found out that u have to use a mask...but can some1 explain how to use that? please dont give a url because i've tried tons and most of them dont help alot

a mask is a black and white picture (white is wherever theres color i think.....) that goes where head will be so it doesnt affect
background when u paint it on (with vbsrcand i tihnk)

oh, paint mask so onl white goes on thingy