Well, if I'm understanding you correctly...
With Frame 3 selected in the Frame Panel, click the "Add Image" button.

Navigate to where you have that custom image on your computer, and select it.
You may have to change the order of that new object you just added in the Object Manager.
Go to the F/X menu and get back to the Turn Page-Film effect; Select Frame 2, and do as you've shown in the image. Source frame 2, target frame 3.