Customer facing emails that originate from Cohub can be customized in your store's active theme. To add emails that can be customized, find the "Emails" folder at the bottom of the theme files list and Add the Email type you'd like to design.
From here, you have a blank slate to design an HTML email. Cohub accepts standard HTML markup, and there are best practices in regards to email design that should be followed. (Best bet is to search for "HTML email design best practices" in your preferred search engine. Typically, laying out an email in a series of tables is the best approach to ensure compatibility across email providers).
Cohub uses the Liquid templating language to access internal Cohub variables for use in emails and web design.