Course reserves are easily selected/curated in the "Library Reserves" section through your Canvas page.
For further assistance, you can refer to the Harvard Library's page about reserves with various access points to get you started.
If you want more specific guidance, you can go to this guide here that gives you detailed step-by-step directions.
If you have any questions, you can contact Priscilla (pmariani@gsd.harvard.edu), the access services specialist at Frances Loeb Library who manages all the course reserves at the GSD.