Splitting the menu

I want to lie to menu to butt up against my header. If I do that my header will cover up part of my menu. So I need to split apart the menu. You can see when I talking about here: https://www.stimadesigns.com/hunterdonbrew/.

I tried placing the menu in the header and using CSS to manipulate the menu but I could never get a space in the center where the header would overlap. I have since returned the menu back to part of the body. I’ve been reading the Codex about menus, but I can’t figure out what to do.

I am not looking for someone to do it for me. I just looking for someone to explain to me what I’m trying to do so I can then go and try to figure it out myself. I learn better through trial and error, but I need someone to help point me in the right direction. What I am looking up is obviously the wrong thing because it’s not working. Can you split the div that contains the menu? Or is there a way to create two menus?

*pay no mind to the appearance of website. I use it to practice on. I originally used it to show someone that their site could be a WordPress site.