Hi plshelp,
Thank you for posting and welcome to the Community Forum!
If your squarespace website is pre-integrated with PayPal payment solution, usually the only thing you need to do is to go to payments/PayPal section on your website and provide your PayPal email address or better, your seller’s ID available in your Profile section.
If you have any challenges I would recommend you contacting the squarespace support as they will be able to direct you to the relevant section of their software.
Alternatively you can review our PayPal Developer website for additional advice: https://developer.paypal.com/docs/classic/products/
https://developer.paypal.com/docs/classic/api/apiCredentials/
https://developer.paypal.com/docs/classic/express-checkout/integration-guide/ECAPICredentials/
https://developer.paypal.com/docs/classic/api/gs_PayPalAPIs/
https://www.paypal-community.com/t5/How-to-use-PayPal-Archive/Need-an-API-username-password-and-sign...
Hope it helps.
Anna
