On the Customization tab, you can edit & manage the storefront theme, design, navigation, add new pages and fully customize the look & feel of your storefront.
Themes - Select any theme of your choice and start building your storefront. All themes are mobile-friendly and work on all devices.
Theme Editor - Make changes to your Homepage, Catalog Page, Category Page, Programs Page, and Author Page.
Navigation - Control & modify your top header navigation here.
Pages - Add additional pages to your storefront (My Account, Sign In, and Sign Out)
Blog Posts - If you have added a blog to your site, you can manage post here
Code Editor - You can modify the template using HTML. Templates are built with Liquid, which is a simple and powerful language.
Assets - Upload images/other assets and link to them via the code editor in Styles & Colors.
Code Snippets - You can add your own custom CSS code to change dashboard or player appearance.
NOTE: If you're looking to further customize your look & feel and need a developer to help you, check out this post on hiring a developer.