Noob having issues with height of background behind menus

Ok So I am VERY NEW and I searched here but could not really find an answer as the problem is hard to describe so I will attach a screenshot




No matter what I change (settings) I cant seem to find out how to make this be the same width. I am a noob so be easy on me. It is a subtle difference but none the less. And also how do I adjust the widthness... I been trying to figure this out for Hours and cant figure it out. OH and how can I spread the menu items further apart from each other..they seem like they are a bit crowded.

I also wanted to know... there is an identical menu at the bottom of my page and I would like to remove it. how and where do I do so?

Please HELP!