Hi Robin,
I don’t think there’s an option in the admin to add a logo in this theme. It’s better to do this using a child theme. You need to delete the site title text from the theme’s customizer (Appearance > Customize > Site Title & Tagline)
Then in style.css of your child theme, add this rule:
.site-header #logo .site-title a {
background: transparent url(imgs/logo.gif) center center no-repeat;
display: inline-block;
height: 100px;
width: 180px;
}
Adjust width and height according to your logo image ( bit bigger is better) and add your logo inside the appropriate imgs folder (or whatever you want to call it – make sure you update the image path accordingly), save everything and you should be done.
I hope this helps.