First you will need to register or login to your shoppers optimum card online at Shoppers Drug Mart. Once you are logged in, you will be asked to provide your email. Then in a few days time, you will be provided with coupons in your email which can earn you points. For example: there can be coupon which will give you 18500 points for buying stuff worth $100 at Shoppers Drug Mart. It will be better for you to install the shoppers drug mart app in your phone if you have a smart phone. Otherwise, if you don't have a smart phone, then you can simply login at the above mentioned shoppers drug mart website and load your coupon there.
When you do buy stuff amounting to the amount mentioned in the coupons, you get that much of points as mentioned in the coupon (Before Tax Amount) that is. You simply ask the cashier to scan your shoppers optimum card for you at the time of checkout. I suggest to always wait for such coupon to arrive in your email, and then load it onto your shoppers optimum card, before heading to buy stuff at shoppers drug mart.