To enter a promo code on https://www.biology-roots.com/store, follow the instructions below.
On a computer find "Have a promo coupon or gift card?" Then click on Redeem your code. This will allow you to enter in your promo code.
On a mobile device it may be in a different location:
If you are having trouble finding it on your screen, you can use the CTRL+F shortcut to search for terms (cmmd + F on a mac), then type in "promo" in the search bar to highlight it.