Theme help

So I am trying to modify the look of my front page but im not quite sure how to do what i want to do.

I am currently using Spacious theme, and i plan to have a slider appear on my front page. however before i can do that, I need to put the site in *fullscreen* as some people have said, where all the widget bars are removed, and no archive or meta stuff is shown on the site. Im not sure how to do so. Thank you in advance.