If you want to use a different picture on each page, just remove the main picture (it's located on the master template). then when you go to the new pages, just add the new pictures but make sure the master template is turned off. If it's on, there's a big yellow bar/warning across the page, and a button that says "return to page'.
If the Master Template is turned on, you'll see the warning in the big yellow bar like shown in the image below. Just click the "Return to Page" button if you want to add something that is specific to just that one page.