If a client's portal is activated, you can share documents with them.
To share a document a client will see in his or her portal:
Navigate to the Documents Tab of a case.
Locate the document that needs to be shared with the client.
Click the arrow at the end of that document's row.
Select Edit Details from the drop-down menu.
A pop-up window will appear.
Under Document Category, select Client Portal from the drop-down menu.
Click Save.
The document will be visible on the Client's Portal.