URGENT! WooCommerce: Need a hook - if status "pending", then "confirm order"

Quick work for a quick buck. I have set up a WooCommerce shop (2.5.2) with an additional plugin where you can confirm an order. But you don't have to confirm the order to change the order status, so I assume it's separated from each other. In terms of automation I need a hook (action/filter) that will confirm the order when the order status changes to "pending". I'm no developer, but I know a little bit about PHP and I found out, that the plugin-author has a public static function with the name "confirm_order". I have attached the two files where this function appears. Please look into it and say if it's possible to find a solution for this or if you need more files. Thanks!