If you are logged in, but you cannot see the 'Work Queue' tab in the YAWL Resource Service, then you are most likely logged in as the admin. Only normal users can see the Work Queue tab, since tasks cannot be assigned to the admin. To see the Work Queue, you need to be logged in as a normal user. If you have not yet created one, you can do so in the 'Users' tab.
A work item will only appear in the user's Work Queue, if the corresponding task is running and offered, allocated or started for the user. To see if any cases are running and to whom task are assigned to, you can log on to the YAWL Resource Service as the admin and go to the 'Admin Queues'.