If you just want lines, create them as a separate layer in a graphics program that supports layers. Delete the image layer. Save as a PNG.
Add this as the top track in Videopad. If the PNG isn't transparent, use the Green Screen effect in to remove its background.
If you want something a bit more complex, first set DUAL DISPLAY under the FILE | VIEW menu.
Begin with your background - a blank clip brown color gradient background here - and drag it up to track 6.
Open the effects window and freehand draw a Polygon Mask in the upper left-hand corner. 
It's the small green + icon.
Add the TRANSPARENCY effect with zero OPACITY and 75% (or so) feathering. When satisfied click the Clear Mask button on the effects toolbar, the one with the red X. (UNcheck the Show Mask box if necessary.)
Add the picture to be inserted into the mask on track 5. Use the MOTION effect to position and size it in the mask area.
Repeat the process in turn - drawing a mask for each corner and adding a positioned/sized insert on the next lower track.
The final mask position will be center, a Circular Mask with TRANSPARENCY and zero OPACITY. The insert image will be added to track 1, positioned and sized..
Takes experimentation, but this can be done with persistence and patience. Here's an example where four corners and the center were created...
Be sure to Save Project File AS routinely, giving it a unique # or name, so as not to overwrite prior saves. Using Save Project Files (no AS) will overwrite. From the HOME tab, that choice is available by clicking the chevron to the right of the Save Project button on the toolbar.
