Hi JenniRose1029,
Welcome to Apple Support Communities. If we understand correctly, you need an invoice from an order that you placed on the Apple Online Store.
You can view or print your invoice using the guidance from the view or print invoice section of Viewing & Changing Orders. If you need further assistance locating that, reach out using the Sales info for your region from Contact Apple for support and service.
If you purchased your MacBook from a local Apple Store or Apple Authorized Service Provider, reach out to them directly for assistance getting a receipt. You can find their information from Apple - Find Locations. You may need to change your country or region from the top right corner of that page to see local results.
Take care.