First, I took some scrapbook paper that somewhat matched our house, and taped it together so it would be big enough to cover the whole matte.Then I used my handy, dandy spray adhesive (best stuff ever) and sprayed the matte (outside!) and then put it on top of the paper.
Cut along the edges of the matte with a super sharp blade
and voila! I put the pictures that came with it back in until we have some
pictures of Peanut and Claire together to replace them with.