GuildWars2WP theme has WooCommerce integrated. All you need to do is install the WooCommerce plugin and activate it.
How to Install WooCommerce Plugin.
To create online store within your WordPress you need to install WooCommerce Plug-in.
Within your wordPress admin area go to
Plugins > Install Plugin > Search woocommerce >install You can add the link "Shop" page to your menu. Shop page is going to be automatically created by WooCommerce. It will prompt you during installation.