UCC images are created using .png format,the resolution must be 256x256 pixels and must be named UCC.png,
place the image file inside your user/documents/archerage/ucc folder (if you don't have a folder called UCC you can make one)
interact with any crest printer ingame and you'll be able to see your image there to preview
(creating a crest will require a crest brainstorm which you can buy from the auction house for gold)
When you're done you'll recieve crest ink which can be used to make stamps (costs memory ink) that can be applied to items that allow it