Navigation Bar Redesign Issues

Hello, I am currently having issues trying to locate how to edit the navbar on my website.

My website has the theme Esteem Free.

They have their own support forums, but there seems to not be much help over there.

Okay, so I need help trying to edit the navigation bar. I want to change when the responsive menu compresses with the min-width. I can’t find that media query inside the files. In addition, I want to change the color of the navigation bar and possibly make the navbar height a little smaller. I also want it to become fixed.

This sounds like a handful, but please bear with me. I am just starting to use WordPress because it is the platform that I am required to work with. I have background on website development having used Dreamweaver and such, but I don’t want to mess around too much with WP’s files because I’ve read around that it’s not very good to do so.

The link to my WP website: http://www.jubileebest.org/