For the gimp download it's this website GIMP - Downloads
and then you want to pick the one at the top that says Gimp 2.6.4
If you looking to use a gloss sealer I used to use 3d deco art and it's available at Michaels in their paint department. Another one I liked was Royal Dimensions not sure if that one is still made or not as I no longer use gloss sealers. I did use the 3d lacquer once but didn't like the blurry quality it had although some people like it I was only able to find it online as my craft stores didn't carry that one. I would suggest just buying the small bottles and see which one you like as it also depends on the paper you use and your ink.