Go to [https://www.klaviyo.com/](https://www.klaviyo.com/) and click the "Sign Up" button in the top right corner.
Create an account and log in.
Click the "Audience" tab in the left-hand navigation bar.
Click the "People" tab.
Click the "Add Person" button.
Enter the customer's information and click the "Add Person" button.
Click the "Purchases" tab.
Click the "Add Purchase" button.
Enter the purchase information and click the "Add Purchase" button.