Branding Cubic Theme

Hi

I am using the Cubic theme for my self hosted site, however I cannot appear to customise it to put in my own logo etc…

I am not able to code very well so maybe it is something I am missing there but in other themes, it was easy to do by the customise menu.

The options on my customise menu are the following:

Site title and tagline

Navigation

Widgets

Static Front Page

Theme

Am I missing something here? The theme was installed through the theme gallery. My website is: https://www.walthamstowweekender.co.uk

TIA