How do you edit the x and y co-ordinates for this keyframe function so that I can have an image come in from off screen to appear as if from out of view?
It's not that hard, click the image you wanna apply the effect (1), than in the effect section, click the "movement effects" tab (2), than "Size/Position" (3)
The button on No. 4 is to add a new keyframe, you have to add one at the begining, with hthe initial; size of the image, than move the cursor (5) to the next position, click the button 4 to add a new keyframe, and than change the size or position of the image .. and so on :) till you move the image as you want.
PS. I'm sure there sould be some video tutorials about this technique. Good luck.