Hello Yücel! Please ask your administrator to open the permission level of your group and ensure that it allows creation of new items in lists:
If it is so, please also ensure that there are no unique permissions on the site (you have the same permission level to the whole site). If it is not possible to avoid their usage, please check that you have enough permissions to these SharePoint lists:
- Tickets,
- Ticket Statuses,
- Comments,
- Tags.