GMOD 10 screenshot problems

hi i have been using gmod on my imac through crossover and was taking some screenshots with the camera gun but i cant seem to get the screens i can find them through the usual windows way but it wont allow me to open them or basically do anything with them any ideas?

thanks

p.s off topic but i was going to use them to make a web-comic based on the show cops like a spoof involving the city 17 metro cops i just want to check no one has done that,

plus any recommendations on software to put it together thanks.

lots of people have done C17 cops spoofs.