Here is my example, I used the maya road chipboard trees as a mask with some glimmer mist, then the glimmer mist wasnt dark enough so I outlined the masked shapes.
![Image](http://www.acherryontop.com/i/gallery2/167030-490.jpg)
but you dont need glimmer mist, you could use paint, or well, I don't know pretty much anything that you can spread over top of what you want to mask.
the category doesnt seem to be showing up in the list when you look at the homepage of the gallery, but you can select it as an option when you go to submit, so no worries! maybe it'll show up when someone adds a layout