Don't put yourself down, it is possible to teach an old dog new tricks!
Keyframes are really easy to use once you undertand the principle.
You have a start point & an end point.
Simply position your Object at the Starting postion on the first Keyframe
Right Click on the Keyframe & select Clone
Move the Keyframe along the Timeline to where you want the movement to end & then position your object in it's end position.
PTE works out the movement in between.
So for what you were trying to do in having a small image move off screen.
1st Keyframe, your image is on screen in it's starting postion.
2nd Keyframe move your image to be off screen
That is all there is to it.
Jill