Modifying elements with Shopify API

[James_J]

Hello, I would like to make Call To Action function as known as CTA.

I already implemented this feature by modifying div width and height but problem is that I can't send those data to Shopify server from client and as I know I can send data by using Shopify API.

How do I make new div element, modify their style, and store the data to Shopify server? Could you show me an example? Thank you.