What do I need to use PayPal API?

I a real noob when it comes to developing applications for PayPal. But, I have a client who needs me to build integration to paypal from his asp开发者_JS百科.net MVC website.

I am not sure where to start looking for answers on how to do this. I don't believe that my client is using Paypal Pro.

Can I use PayPal's API without a PayPal Pro account?

I think that you can get started here - https://merchant.paypal.com/cgi-bin/marketingweb?cmd=_render-content&content_ID=merchant/wp_standard