You can start the purchasing process on the view for a particular event with a clear indication to buy the ticket(s). The event can be for anything: music, sports, theater, travel (even spaceships), etc.
The minimum sequence should be: Add ticket(s) to checkout, checkout view, shipping information, payment information, success.
You can ignore error states.
You can assume the user is checking out as a guest without the need for login.
You can design this experience as a desktop or mobile website.
You can collapse or re-arrange the sequence of steps as you see fit.