Once you’ve added the data for your submission, see the link below the empty image frame that says Add or edit images. Note: This is a separate step from the submission form.
In the image box on the left, click 'Browse' to select an image from your local files, or drag and drop an image from your desktop or a browser window into the Posterogs page. You can select and upload several images at once.
If you would like to reorder the images, simply drag and drop.
When you've added all the images you want and they're ordered as you want them, click 'Save' in the top-right. To go back to the book page, click the poster title at the top-left of the page.