Provided that you haven't hidden the Firm Feed, it can be found in the following locations:
The "Firm Feed" sub-tab of the "Practice" tab.
Matter Details Page
A Matter specific Firm Feed can be found on the details page of any Matter.
Clio Connect Contact Card
Additionally, the "Firm Feed" sub-tab can be found on the Contact card for any Contact that is also a Clio Connect user.