API credentials to integrate my application to RingCentral Faxing system.

Hey Joe,

You're asking your questions in the right place now sir.

1. Have you setup your Test/Sandbox Account per our documentation?
2. Have you stepped through the Getting Started documentation which will help you create an application and obtain your API keys sir?

You must start at the beginning to make sure you're environment is properly configured for development sir.
Let me know where you're at with these things, and if this helps get you moving in the right direction.

Benjamin