I need a copy of my receipt

Did you buy the product directly from Apple within the last ~18 months? If so, you received an e-mail conformation and there is a link to an invoice in the upper right of that message:

If it as been more than ~18 months, you need to contact Apple and they are not here. This is a user-to-user community.

If you bought form a reseller, Apple cannot furnish you with a receipt. Only the seller can.

If you have the original, just print a copy of it.