Configuring Commerce in an existing drupal install
I would recommend that you install and play with Kickstart 2 in order to study best practices and find out what contrib modules you need for the most common Drupal Commerce features.

To install Drupal Commerce on any existing Drupal site, start by first installing its dependencies, and then activating Commerce modules in the order indicated here. Also, make sure that you activate all the Commerce UI modules. This should get you to the point where you can create basic products, orders, and a checkout workflow.

You should first learn about the separation between product displays and products here.
In short, you need to create a new node type, let's say "Product display". For it to act as a product, you need to add a "product reference" field and configure it to suit your needs. Make sure that on the "Manage display" section of your Product display you have selected the "Add to cart form" format for your product reference field. Your view should display products with add to cart forms as long as you configure it to display nodes of type "Product display" with the correctly configured view mode.

After you understand the concept, I fully recommend installing Inline Entity Form. It will spare you the effort of explaining the above concept to your clients, and make their life much easier.