What version of Premiere Elements do you have and on what computer operating system is it running? Is your program Photoshop Elements or Premiere Elements?
So, for now generalizing...
In Premiere Elements, you can use the shortcut (Rotate 90 Right or Rotate 90 Left) by selecting one of those choices from the pop up menu after right clicking the photo.
You can highlight/select your Timeline photo, go to Properties Palette (versions earlier than 11) or Applied Effects Tab/Applied Effects Palette (versions 11, 12, or 13) and use
the Rotation feature in the Motion Panel expanded. This is what I believe that you are seeking.
Please supply more details so that we can fine tune our reply.