Putting Menu Bar in Header

Hey Guy!
I had a few questions about my website today.
As of now my menu bar looks pretty lame and makes my website look somewhat unprofessional.
students-united.org

I would like to know how to change the font, text size, and color of the menu bar but mainly how to put it in the header.
If you do not know what i mean check this out.
https://www.archaeoadventures.com/
If my header and menu could look like this that would be perfect!

Any help is appreciated

Thanks,
Colin