Can I put a photo on the back cover?
Yes. Alongside your front-cover artwork you can add a separate back image, and it fills the back panel of the wrap the same way your front art fills the front.
Adding it
In the Back Cover section, use Back image… and choose a file. It's independent of your front cover — a different photo, a texture, a pattern, or the same art continued.
Keeping the blurb readable
A photograph behind body text is almost always a legibility problem. Text over a busy sky, or over anything with strong light and dark areas in the same paragraph, becomes hard work to read no matter what color you make it.
Use the Frost behind blurb slider. It blurs the photo in a panel behind your blurb text, so the text sits on something soft and even while the rest of the photo stays sharp. The slider runs from off upward — a little is usually enough, and you can leave it at nothing if your image is already quiet in that corner.
Beside it, Frost is dark flips the panel to a dark frost, for white text over a light photo instead of dark text over a bright one.
The frost is part of the artwork, not a preview effect: it exports into the print PDF exactly as you see it.
Where the author photo goes
There's no separate author-photo slot. If you want a portrait on the back cover, add it as an image layer and drag it into place — see Cover layers: title, tagline, and extra images. Layers sit above the artwork, so your photo will never be buried under a back image you add later.
Hardcovers with a dust jacket
A dust jacket has flaps as well as a back panel. The flaps are their own text fields — the blurb does not move into them automatically, so a jacketed book gives you three separate places to write: the back panel blurb, the front flap, and the back flap. The back image still fills the back panel. See Paperback, hardcover, or dust jacket.