Theme development question

[ginagregory]

Sorry to post such a basic question, but I'm struggling to find the answer in the Arcadier docs/support articles.

How is theme development done? From what I can tell, you pick a pre-made theme and then any customizations have to be done using only the CSS Editor or Custom (javascript) Codes. How do I get access to the template source code files? What templating language is it?

I'm coming from a Shopify theme development background where there's a group of template files that use the Liquid templating language, but I can't find anything about how this is done on Arcadier.

I'm guessing that custom theme development can only be done using the Arcadier APIs. I'm not a back-end developer, so I'm having a hard time figuring out how to get into the front-end theming part.

Thanks for your patience and guidance.