You can add attachments to a workspace by clicking the File Archive button on upper left toolbar or navigating to the menu Workspace->Document Archive.
The document archive supports drag and drop functionality for files and folders.
To add attachments:
Click on the “document archive button.
Upload a file.
Edit, lock, or delete attachments
To delete or edit attachments hover over the file, click on the drop down menu and select the action you wish.
You can also lock and edit the attachment from this drop down. This helps you manage versions of non-ardoq documents.