can you tell me please

First you go into your Toribash folder. Then there should be a heads folder. Copy a picture that you want for your head into there and it has to be in .tga format. Rename the picture file to your ingame name and then the picture should show up.

how do i make my own?

You draw one in the program of your choice, please read this: http://www.toribash.com/forum/index.php?topic=327.0