Not sure if the question is still relevant, but just in case.
Go to your message page by clicking on the envelope ico on your avatar in top right corner and the down pointing ico next to dismiss at the bottom of the window.
Click the new message button.
Send the message to discobot with any subject text and put the text ‘@ discobot start tutorial’ in the body. Note there should be no space between the ‘@’ and ‘discobot’, which I left to ensure the robot was not awakened by this reply.