Steps:
Open the profile of the user you want to message.
Tap the Messages icon in the top right corner.
Alternative way:
Open your messages by tapping the Messages icon (top right) on the home screen.
Tap the Author icon (top right corner).
Search for the user and start messaging them.
Good to know:
You can mark messages as unread after opening them by long-pressing the last message from the user and selecting Mark as unread at the top of the menu that opens. After you select this a red notification will appear beside the chat in your messages tab to indicate an unread message.
If the user is not following you, your first message will be sent as a request. You cannot send more until they respond.
Some users may have settings that prevent others from messaging them.
Be respectful: do not spam, send repetitive messages, or harass users.
You can report abuse, block/mute users, or pin messages within messages.
Currently, direct messages support text only — voice, image, and video attachments are planned for the future.