How do I expand the area around the stage?

I just can’t figure it out. How do I expand the grey area around the stage so I can ad more graphics to my platformer game. I know how to expand the stage itself… but not the grey area around it. I use vcam so the screen follows my character, so all graphics are on the first frame. the character keeps moving to the side so I need to keep ading graphics for a long way to the right, but the way it is now, I run out of room.