You can access all your boards as well as boards in channels you belong to in the Boards dashboard. Select Boards from the Product menu in the top-left corner of Mattermost to open the dashboard and switcher. You can also select the Boards icon in the channel header to open the board for the current channel, Direct Message, or Group Message.
Boards uses channel-based permissions, meaning that all members of the associated channel can access (read/write) the boards for that channel.
To create private boards:
Create or join a Private channel, Group Message, or Direct Message.
Select the Boards icon in the channel header.
Create a board.
You can share a read-only version of any board with anyone who has the link.