How to add/edit custom made tattoos to my player..

Hi i have been searching for any tutorials but i ddn't find one. i know there is a package of cutom made tats but i would like to make one myself. unfortunately i dont know how. i have used the mod tool to extract "pcarmtats.iff" and managed to extract some. but the image extracted is so small and shows a black background and a blue outline of the actual tattoo. and i don't know how to edit that. anybody can help me? i have another question too are all myplayer files in the .cmg save file or there are .iff files that i can edit. but wanted to edit the tattoo of my player. so anyone? Thanks in advance for the help. ))