Need help adding widget area to my header

Here is the link: https://www.illwilldesigns.com

In the header area, there is the logo on the left, and a top nav on the right, *I actually want to get rid of the top nav, I have found the code in firebug but cannot find the code in wordpress or FTP anywhere!* But, I am looking to add a widget area for an ad banner to display on the right side of the logo.

If someone helps me with this, I would be very thankful!! I dont post until I have no luck in searching the web, which is rare lol. Thanks!!