This depends on the type of airline you are flying with. There are 2 options:
1. Low-cost airline (such as Ryanair, Transavia, easyJet and Wizzair)
Your confirmation email you will receive immediately after booking is also your ticket.
2. Other airlines
After booking, you will first receive an email with the booking confirmation. You will receive your ticket via email within 18 business days (but no later than 24 hours before departure). If you are booking within 24 hours before departure, then you will receive your ticket via email immediately.
Make sure to also check your spam inbox. Did you not receive or did you lose your ticket? Log in on MyGate1 and go to ‘Your Booking’.