[Plugin: NextGEN Gallery] Mini Icon over thumbnail and single image

Hi! I have a question and I’m wondering if anyone can help me with that. I’m trying to implement this style of gallery in my wordpress site with nextgen gallery. I need to use 3 different icons for 3 different ngg TAGS. I really don’t know how to do it, I’ve been trying but it doesn’t work. I was thinking in using 3 different template styles for each icon, but I don’t know how to asign them to images. I really don’t know php or codex. Thanks for any help.