My card below is using the masking technique. I saw this technique here http://stampwithtami.com/blog/2012/01/butterfly/
Tami has a great video too to go along with her post.
Firstly, you take a shape die and cut out your mask. Adhere this to the front of your card and then sponge inside the cutout area. Ink up your image (I have used lovely as a tree set) in black and stamp your image in the masked window. Take off your paper and then stamp your greeting.
Stamp set used: lovely as a tree, curly cute
Cardstock: whisper white
Inks: tempting turquise! Marina mist, tangerine tango and more mustard
Accessories: labels collection framlits