Go to Support > Tickets > New Ticket. Pick a Requester (search an existing contact, "Add me", or "Add new contact"), then fill Subject, description, optional Attachments, Assignee (Auto / Select agent / Leave unassigned), Priority, Team, response and resolution due dates, Tags and Watchers. Checkboxes at the bottom control silent creation (no notification email) and "Stay on page". Needs create_support_ticket.