If you have received a notification to join an ongoing log, you will see all active logs on the dashboard of the app. Tap on the log to view the log.
When you have entered the log view, you will see the log feed that is being updated in real-time for all users that has access to the specific log.
The contents of the log will update automatically, so you don't have to do anything for the log to update.
If there are images in the log, you can view them in full-size by tapping on them.