Messaging and chat
Open the person's public profile, choose Message, then write your message and send it.
Once it is sent, you are taken to the chat in your inbox. If you two have talked before, you land in the same chat.
They get an alert in Signr and by email, unless they turned those alerts off.
You need to be signed in with your own profile. If a profile has no Message button, that person can't get messages.