Pick Lists can be printed in the Orders section of your Fillz account. Sellers use these to pick items for shipping (they contain locations of the ordered items if you populated the location field in your listings).
To print a pick list, go to Orders -> Browse and click the "Pick List" button under Order Status. You can then select the status of the orders that you want to print and click the print button on the top right hand side of the page.
For more information about processing orders and printing pick lists, click here.