Adding a Block on the Center of Full Column page

Please see attached screenshot.. I created a new page & added a "full column" and then added a Block within the "full column".
It works fine, but the Block is left justified within the full column, I would like the Block to be on the center instead.. is it possible ?

I also tried to minimized the page width, but I could not go less than 774px. Is it possible to make the page width around 600px ?

Thanks !
@AJ 

Could someone help please ?
I am also trying to make the width of the top header/menu  smaller (around 600px), but not sure how to do that.. please see screenshot from my prior post..

Thanks ! 

/administration/templates.php?mode=settings

Minimal Allowed Page Width (Pixels)