Hello @emilcharter ,
This guide explains all of the fundamentals:
Also, here are some other guides for further information:
Also note, however, that you cannot send a message to a user in a concluded course. So, if you are trying to contact a teacher from a concluded course, that would be why you are having some trouble.
If this didn't help, you might want to clarify your question.
Hope this helps,
Michael A. 🙂
Hello @emilcharter ...
In addition to the helpful information that you've received from @bneporadny and @michael1439273 today, another option for you is to go to your "Help" menu on the left-hand side global navigation bar within Canvas. Then, click on "Ask Your Instructor a Question". See https://community.canvaslms.com/docs/DOC-10554-how-do-i-get-help-with-canvas-as-a-student for more information.
I hope this will be of help, too, Emily. Please let Community members know if you have any other questions about this. Thanks! Be well, and stay safe!