From the main admin centre, head into the customer section where you will have the ability to search for a customer

Now you are in the customer section, you can search for a customer via the search bar. There is also a filter option if you're unsure of the customer name. Things such as order ID, email and external ID can be searched via this section

Once you are in the customer, head down to the bottom of the page and you will see an option to add attachment

Press this button

Now that the add attachment option has been clicked, a window will appear where you will have the option choose a file and also add a note

The reason you may want to add a note is so that it is visible to others what the attachment is and why it was added

Once you have chosen the file and applied this, you will then see the attachment appear below. From here, you can download, edit or remove.

It is worth noting that you can also add the attachment when clicking onto the order directly

This is mainly used for when products are returned to take a picture of item condition