Incoming questions to 'Open tickets' can be handled by all agents.
Agents or administrators can use the 'Assign To' function in the inbox in order to assign a ticket.
Agents can see the tickets assigned to them in the 'My tickets' branch.
1) To see tickets go to Ticketing -> Open Tickets
2) To assign tickets to agents by clicking on the "Assign To" button on the upper toolbar (in the 'Open tickets' by checking the question or inside the question) and selecting the agent from the list.