There's an easier way to slide an image onto the screen - animate it. http://help.nchsoftware.com/help/en/videopad/win/effects_animating.html
Open the effects window for the image clip and choose POSITION.
In the preview window drag the image off screen, or use the sliders, as shown below. Then click the small green + sign in the toolbar to set a keyframe.
Move the red cursor to the right, to a position where you want the image to be full screen.
Slide the image to full screen. The distance between keyframes (shown by dots) determines how fast the image will move. Shorter distance = faster.
DRAG.mp4