Message your coach

Messages is where anything your coach sends you lands, and where you reply.

Steps

Tap Messages.
Tap a conversation to open it, or press Message a coach and pick a coach to start a new one.
Type in the box at the bottom and press the send button. On a computer, Enter sends and Shift with Enter starts a new line.
Go back to the list with the arrow at the top left.

If you are under 18 you cannot start a private one to one thread with a coach. The page says so: a parent or guardian messages your coach on your behalf. You can still read everything sent to you and reply in any thread you are already in.
A parent can open a shared thread with you and your coach in it together. Everybody in that thread sees everything, which is exactly the point.
Once you turn 18 you can start a thread with a coach yourself.
Nothing in Messages is anonymous, and your coach can see the whole thread.
If something is worrying you, tell a parent, guardian or your club's safeguarding officer as well. A message in an app is not the place to sit on it.