Resizing sidebar – expound theme

I am attempting to insert my Adsense codes into my website but my 728×90 ads extend into my right sidebar. Can someone please advise me where to edit my expound theme’s files please? Either make the sidebar narrower or main content wider.

An example of this occurence at my website can be found at https://shootingtime.com/new/adding-compound-bow-accessories/how-to-install-an-arrow-rest/

Thanks!!