Returning an Item

Hey! So I live in the UK and I have an item to return. It has to be sent to Germany. I was just wondering what I do with all the Proforma Invoices that got sent with the shipping label. There are no instructions as to what to do with them. It seems that there were three copies that we sent with the initial email. Do I put one n the box? If anyone from the UK has had to return a item your help will be appreciated, Many thanks, Tom