What version of Premiere Elements are you using and on what computer operating system is it running?
For now I will just assume Premiere Elements 11, 12, or 13 on Windows 7, 8, or 8.1 64 bit.
You can rotate your Timeline video in at least 2 ways
1. Right click the Timeline video and, from the pop up menu, select Rotate 90 Left or Rotate 90 Right
2. Highlight the Timeline video, and then go to Applied Effects Tab/Applied Effects Palette/Motion Panel expanded
and use the Rotation feature there.
Please let us know if any of the above worked for you.