To change the default sort order of your products first goto:
Appearance > Customise
Woocommerce > Product Catalogue
Now you can change your preferred default sort by selecting from the default product sorting drop down, by default its on "custom ordering/name". We will show you how to add custom ordering to your products next.
If you would manually like to decide the order of your products leave the above option on "custom ordering" and then go into each one of your products and in the advanced section add your preferred order number in the Menu order box.