During a desktop to desktop Sylo session, you can add documents/media to your session:
1 - During your session, click the 'share a file' paperclip symbol located in the bottom right corner of your screen.
2 - Select the desired item from local folders on your computer and press 'Open'.
3 - The item will be uploaded to the file area, available to view and download by both participants in the conversation.
Note this feature is not available in the Sylo Mobile Apps.