Login at Chatbooks.com- from here, in the upper right-hand corner, tap "Bookshelf":

There, you'll first see "My Subscriptions." From here, tap into your Subscription.

You can tap into the Monthbook you want to add photos to. Once you've clicked into a specific month, tap the + button. You can either use your Computer, QR Code to pull from your device's photos, or Google Photos to pull photos from.

You can add a Caption, adjust the Date and Location, the Page layout by tapping on 1 photo.

If you'd like to adjust more than 1 photo at a time, select an option under "Batch actions."

Once you've added at least 30 pages and a maximum of 60 pages, you'll be able to send your book to print.

Learn how to add photos to your subscription from the Chatbooks website here.