To use RingCentral for sending faxes, log in to your account on RingCentral.com and navigate to the Faxes tab, where you can enter phone numbers, choose a cover sheet, attach files, and send the fax. The process may take a few minutes, but you can monitor its progress through the app. Additionally, RingCentral integrates with over 1,500 other apps using Zapier, allowing for automated fax sending capabilities.