cropping video to 3:1 format screen
 

I am so new to video production that I haven`t even chosen an editing software yet. But I want to convert my formerly nine analogue projector slide-show on the Alps to digital and project it with video beamer onto my 6 x 2 metre screen. This is clearly a non-existent format in the video realm, so I guess I would have to crop the whole production top and bottom to provide the wide panorama. I haven`t a clue about how to go about this. If anyone could start by pointing me in the right direction I`d be very grateful. I`d prefer to remain with one beamer - perhaps a 1920 HD one, with vertical dimension cropped to 640 I guess