The green Chat button means a Psychic is online and available NOW for Chat.
This button can be found by the Psychic’s name on the All Psychics page and on the Psychic’s full profile page. Tapping it will open a Chat window and will load (if any) past reading history you have with the selected Psychic.
Once in the chat window, you can type your message and press enter or tap the send button. Once the Psychic sends their first response, your Chat will officially begin, a timer will display, and billing will start at that point.