Web app on browser: RingCentral Web Version
To send a new message on RingCentral, click on the "notepad" icon as indicated in the screenshot.
Another way to message a person is through the search at the top:
This will open the new message pop-up in the middle of the screen. You can type the name, email address and or extension to bring up a list which you can select the people you want to message. This can be solo or group messages.
You can hover over individual messages to bring up options(Similar to Microsoft Teams).
There are more options to upper right-hand corner when messaging someone. Hovering your mouse over them will indicate the name of the option.
Message settings can be found by clicking "Settings" at the bottom left-hand corner
Contacts contain everyone who has activated their account. It will show their name, email address and extension. Hovering over them will give you the option to message or call them. Clicking on them will give you the option to send a message, start a video call, phone call and or fax.
For more detailed help: