How to add Extra Widget Areas?

My website is: https://www.mintconditioncustom.com

I currently use the Twenty Eleven theme.

What I would like to be able to do is have a space above the header to fit an ad. There is currently no widget space for “above header” in the theme I’m using. I don’t know if there is a way to add extra widget space, but if so it would be greatly appreciated if someone could tell me how.

And I’d like to add a widget area “above the blog” as well. What I mean is, I want to be able to have something above the blog and just under the header. Even if it’s ad space, or a “welcome” message or anything like that. I realize I could just make it a normal post and make it sticky so that it’s always at the top no matter what, and if this is my only option then that’s fine. If so, is there a way for me to disable the posting date and time stamps and disable comments so it doesn’t just look like a regular post?