Start a 1:1 or group chat in the Microsoft Teams mobile app to talk privately or collaborate with a smaller group.

Start a chat
1. Tap Chat -- New chat
2. Add a contact(s) to talk to
3. Type a message and tap Send

Add a group chat name
1. Tap the top of the chat
2. Tap Group chat name
3. Type in a name and tap Save
4. A group chat name makes it easier to find later

https://support.microsoft.com/en-us/office/start-a-chat-on-the-go-9c7b1258-28f0-434a-a341-569ea0b36f05