This section of the Getting Started Guide is slightly incorrect. The steps imply that after inserting the Add to Cart button, the text selected, [insert button], will be replaced with the Add to Cart button. However, eCart no longer replaces content when an Add to Cart button is inserted, to help avoid overwriting important data.
However, the steps should still lead you to successfully adding the Add to Cart button to your page. Once the button is inserted, just manually delete the [insert button] placeholder text.
This process does not add the name of your product, description or price. Instead, the Add to Cart button is simply the function that connects your product's detail page to the cart page so that customers can purchase an item from your store.