You can search for the user of you have a higher role on the system and simply click the name. You will notice there should be a "message" option. The same goes for inside a course in the "participants" section.
Let us know what your role is and where you are trying to do this and we can be of more accurate assistance.
Thanks for your reply.
So if there are ten students enrolled in Course, so they can search for other user in that course. and it will work ? right ?
and Teacher can search of all students as well ?
No problem at all. The course setup will also determine if users can do this, especially for students, if you use separate groups, then they will not eb able to see each other in courses.
The user should be able to open that chat bubble and search for another user to message as well.
What is your role on the site and on what level do you have this role?