What to "put" on the sides of the site?

Question

Bootstrap

Hello. There is an idea for the site, and there is already a design for the header, main objects, individual pages. But, what if I want to make 2 indents around the edges, what should I put in there (this space will be used for advertising, but not for the entire site (that is, for a couple of separate blocks)), how to fill this area ??? not to look cheap

Answer 1

Make it like one of the not at all cheap social networks, shove it there ... nothing ...