THIS STEP SHOWS TWO EXAMPLE SETUPS. As long as there is no nonwhite background visible (or it is correctable in post), build this how you see fit.

When using posterboard, use the MATTE side. Glossy materials and light do not mix, and reflect light in ways not found with matte materials.

Setup a backdrop support. This can be anything from a trifold board cut in half (the style you used in "school") or a custom design. I chose a custom design to conform it to my design spec and make the modifications I wanted.

Setup your white background. Once the backdrop is stable, minimize as many unsightly areas as possible. You are ready.

Take a few test photos (Optional). If you are unsure about the end result, take 1-2 test shots for review. Make adjustments until you are happy with the end result.