Here's the default "new ticket" form we have in Jitbit Help Desk:
You can add some extra fields for the end-user to fill out, for that follow these steps:
You've justt added two custom fields to the ticket template:
Now you have two optional fields in the UI for your customers. But that's not all. You can have pre-filled ticket text too, and make this text depend on the selected ticket category.
Here's an example