[Hen Virgin]

Hello, In premier pro (could be after effects) I am making projection artwork (30 mins) for irregular wall – the projector is 1920 x 1200 resolution. Our artwork will fit the wall at a resolution of 1320×1200 : My question is > how do I block off the 600 pixels ? as I have to put alot of stills and movie clips in the 1320 x 1200 ?? How can I best block off the 600 on the left ? Please advise !! Thank you !!

ps If I block off the 600 – how do we make it so no light is projected from it ? is it black video / transparent video or something else ? Please advise