Add logo in venom theme

I need to add a custom logo to this website but as it’s a free theme there’s no option to edit the logo. If I try to add it through custom css by changing
.site-branding class, it just gets overlapped by the current text and there’s no option to edit the current .site-branding text
Please anyone help me as I’m a beginner in wordpress.

The page I need help with: [log in to see the link]