To see existing attached pictures:
On main screen, tap Packages at the bottom.
Tap a package.
The picture should appear on this screen in thumbnail size, which can be tapped to see a larger version.

To add or delete another picture:
With the package open, tap the pencil button at the top.
At the bottom, tap Next twice.
To add another picture, tap "Upload your files here". This allows you to take a new photo, or select an existing image from the device's photo gallery.
Existing pictures are shown below the Upload section. An X button on each existing picture allows you to delete.
Tap Save when done.