how to add header to this theme!?

Hi all,

I found a theme I love but don’t know how to to add my header (well more of a typography logo) there is no current header, just the site name and it’s stumped me!

I’ve loaded the .png I just don’t know where to add the code to get it up there
+ Is the code I need`img src https://www.chrissayburn.com/Emerge/header2.png

My site is https://www.chrissayburn.com for reference.

Thanks for your time, any help or pointers would be much appreciated!