Usually, you'll come across a QR code or a link which leads you to your loyalty card.
Every time you buy something, simply present the loyalty card from your phone. Your card comes with a unique QR code. The store's staff will scan this code, allowing them to add points to your account.
Once you've accumulated enough points for a reward, open up the specific reward and hit the 'Claim Reward' button. This will generate a QR code which the store's staff can scan. Your points will then be subtracted, and the reward given to you by the staff member.
No, the staff will only be able to view the name you provided during registration - which can be any name you choose - and your unique membership code. Rest assured, your email and other details remain private and won't be visible to them.
Business owners can view your email address and name, and whether or not you've given them permission to send you special offers. They won't have access to any other personal details.