To send a private message, first click New chat at the top of the app to start a new conversation. Type the name of the person or people you want to chat with. Then, compose your message and click Send .
You can include up to 50 people in a group chat.
Add people to a private chat (start a group chat)
To loop more people into a private conversation, just click Add people in the top right corner of your screen. Then, type the names of the people you'd like to add, select how much of the chat history to include, and click Add.
Note: Currently, you can include chat history only when adding someone to a group chat (not a one-on-one chat).