How to make the "wipe" transition with vertical line in Premiere pro cs6? How to make the "wipe" transition with vertical line dividing the image during transition in Premiere pro cs6? 

Transitions like that is most often used in the demoreels, showing process of creating shots "in layers"?

Thanks in advance!
Depends on your idea. Simplest way is using a Linear Wipe Effect (on the strip above). For more complex transitions I'd suggest to animate a rectangular mask path in order to get most control, see the manual: https://helpx.adobe.com/premiere-pro/using/masking-tracking.html