Your ticket includes an entry pass - a QR code the organiser scans at the door to check you in.
Open your entry pass from the link in your confirmation email or from your downloaded ticket.
Show the QR code at the door. Staff scan it and you're in.
The pass shows the event, time, place and your booking reference, so everything you need is on one screen.
The pass page itself can't check you in - only the organiser's scanner can, so a screenshot shared around won't let someone else in on your booking.