When you're about to reply, click the "Go Advanced" button next to submit, then scroll down to Additional Options -> Attachments -> Manage Attachments. There you should be able to upload files.
However, since the save is 0 bytes, I doubt that would be very helpful.
What kernal is your friend using? The official one, or Wood R4. Try Wood R4 if you aren't, and if your cart supports it.