What kind of cover image should I upload?

Upload one image: your front-cover artwork. That's the front panel of the book. The Cover Maker takes it from there — it extends the artwork's color across the spine and back, and lets you add the title, author name, blurb, barcode, and spine text.

Good front images are:

• High resolution — see What resolution should my artwork be?
• Roughly the shape of a book cover (taller than wide). The editor can fit or fill, but art close to your trim's proportions needs the least adjustment.
• Without your title baked in as gibberish if it came from an AI generator — add real title text in the editor instead. See How do I make an awesome front cover image?

You do not need to build a full wrap in Photoshop — that's exactly what the Cover Maker is for.