Hello Sovattha and welcome to the forums!
Do you happen to have WooCommerce installed? The option to sell tickets will only display if Event Tickets, Event Tickets Plus and an ecommerce plugin (like WooCommerce) is installed. I’m wondering if that could be the issue.
If you do happen to have that active already and the ticket options are not still not showing, then I would definitely take you up on that offer to see the information in the Help tab. You can copy that and paste it here as a private reply and I’d be happy to look it over.
Thanks!
Geoff