1. From the Storyboard, tap the 'Text & Image' page that you would like to edit.
2. Tap the "+" icon to add a new image to the page.
3. The Media drawer will open for you to make a selection.
If your "All Photos" and "Albums" folders are empty, you need allow the app to access to your device photos and videos. For instructions, see this article.
4. Upon tapping to a select a new image, it is added to the page. Next, tap "Done".
Tapping multiple images will add all of them to the page (up to 6).