I am having trouble rotating videos. I go to the video effects and click on rotate and shear, but nothing happens. Anyone having this issue or know how to solve it?

I typically rotate my videos before importing into KDEnlive using mencoder (which comes with mplayer).

For example:

mencoder -vf rotate=1 -o OUTPUT.AVI -oac copy -ovc lavc INPUT.AVI

mencoder -vf rotate=2 -o OUTPUT.AVI -oac copy -ovc lavc INPUT.AVI

Do i enter that in Terminal?

(Linux Newb)

Yes.
What versions of Kdenlive and MLT do you use?
Rotating works for me.