Adding Navigation bar to pre-exsisting template

Hi, on my website http://www.thelegalhustle.com
I’m having trouble figuring out what file to modify to add a navigation bar at the top of the site, as well as what code would be a good base starting point –I like the sidebar and want all of that to stay intact and I would simply like to add very viewable “about”, “Contact” and “Forum” tabs at the top…

The template i’m using is called “upstart-blogger-minim-01”