First of all, here is a video explained how 2-way message and auto message looks like from desktop version:
Menu -> Setting -> Auto message

In the message setting, you can turn on/off specific auto messages; You can also customize the message
New appointment is booked
Once turned on, our system will send a message to your client right after the appointment is booked.
You can edit message content anytime.
Appointment is rescheduled
Once turned on, our system will send a message to your client the new appointment time right after the reschedule is saved.
Appointment is canceled
Once turned on, our system will send a message to your client that the appointment is canceled.
Unconfirmed appointment reminder
Once turned on, and if you select “send by One day before”, our system will send a confirmation message to your client one day before his/her appointment begins. If your message content include “Reply ‘Y’ to confirm”, once your client reply “Y”, the appointment status will automatically change from “Unconfirmed” to “Confirmed”.
Pet birthday reminder
Once turned on, our system will send a birthday message to your client on that day. You can always customize the message content.