In order to setup the API for your PayPal account, you'll need to log into your PayPal account and go to your Profile.
Some PayPal accounts may have a different view then shown below:
If so, you can see the "Request API Credentials: preferences under "Account Information" as shown below:
Then follow instructions per Teapplix; Setup; PayPal; API Integration.
If your PayPal account looks like the example shown below:
Then click on 'More Options'
Go to API Access and click on update and follow directions per Teapplix; Setup; PayPal page under API instructions.