By tapping anywhere on the page
1. Tap the Image Tool from the toolbar
2. Tap anywhere on the page
3. Select an image you want to add from "Photos" or "Insert from..." and choose from your Files.
From the contextual menu
1. Tap the Image Tool from the toolbar
2. Select one of the images you want to add to the page or drag and drop the image thumbnail to the page from the contextual menu.
Adding an image as a whole page
1. Tap the Add page icon near the top-right corner of the Tab.
2. If necessary, tap Before, After, or Last Page to indicate where the new image will be in relation to the current page.
3. Tap Image, then select an image from Photos.