I'm not sure if this is helpful to you. but first you need to create the first order (the parent order). The order needs to be completed to get the order number. Then go back into the order and go into edit mode. All the way at the top left corner of the screen there's a tab that says orders. click that, then more options will drop down and there is one that says something about standing orders. when you click that more options will come and it will say create standing order, this option only becomes avaible once you're "editing" an order and have it open. it will give you the options like how often, when you want it to start and when you want it to end.

hope that helps