Before you use this environment, you have to register a developer account on http://developer.paypal.com and create two test accounts.
1. Open http://developer.paypal.com in your browser and click on Sign Up Now.
2. Fill in the fields and click Agree and Submit.
3. Log in to your developer account with your e-mail and password.
4. Click on Create a preconfigured buyer or seller account.
5. Select Buyer (Use to represent your customer's experience) and fill in the field with any test data. Click Create Account.
6. Create another account, but this time choose Seller (Use to represent yourself as the merchant) as the Account type.
7. After both accounts are created, click on Test accounts on the left hand side. You should see an overview of the test accounts as shown in the following screenshot: