How do I set up a free Bitcoin eStore I want to sell digital products (eBooks) using Bitcoin, and I want products to be instantly available after purchase. What could I do?
Coinbase has shopping cart plugins that can integrate with many existing e-commerce web apps without you having to write any code. See here: https://coinbase.com/docs/merchant_tools/shopping_cart_plugins.

In case you were wondering, an "e-commerce web app" is a pre-build shopping website that is analogous to Word Press for publishing. There are a few open source (free) options for this. Just google "open source e-commerce web app".