Add content and notes to a team in Microsoft Teams
You can upload files or folders directly to the Files tab or create a new file in any Team channel.
Upload a file or folder:
Create a new file:
Note: Creating a new file stores the file or website within the team channel. To store and notify channel members about your link, create a link in a channel message.
To add an existing notebook to a channel, see Add a OneNote notebook to Teams.
You can upload files in the desktop or web app, and view them on your mobile device any time after that.