WHCC's editors drop directly into your ordering flow: your user configures their product inside the editor, then returns to your app to check out.
You can supply two versions of each image: a lighter, optionally watermarked copy for the user to work with inside the editor, and the full-resolution, unwatermarked file that actually gets printed. See the url and printUrl fields on the photos array in Creating an Editor.
Learn how to Create an editor