Premiere Elements 12 Mac
1. Highlight/select the video on Video Track 1, go to Applied Effects Tab/Applied Effects Palette/Motion Panel expanded and use the Rotation feature in that expanded panel.
2. I am not sure how this works for Mac, but with Premiere Elements 12 on Windows, you right click the file on the Expert workspace Timeline and select either
Rotate 90 Left or Rotate 90 Right in the pop up menu that appears after the right click.
Please let us know if that worked for you.