Installing WooCommerce

From your dashboard hit Plugins > Add New > Search for WooCommerce.woocommerce 

Click on install, activate the plugin and it will take you through a setup wizard.

Back to your dashboard, you'll need to download another plugin called Genesis Connect for Woocommerce. genesis-connect

Once you got all that done you'll want to go WooCommerce > Settings Here you'll set up the size of your product photos, taxes, shipping, payment gateways, etc.