How exactly you answer a ticket is up to you and will vary greatly, but the mechanics of Zendesk are the same.

1.  Ticket Number is used for referencing the ticket later

2.  Assignee will show the current support members.  Choose to Take It before submitting your answer so that replies will come back to you directly.  If the ticket should go to someone else for various reasons, you can use the drop down menu to select a different staff member, and "Submit as New"

3.  Customer's Name may not always be the person you're talking to, but it's a good starting point!

4.  Purchasing Email isn't an exact science.  People often forget what they used when they bought the license, so if nothing comes up with that email, try searching for the one they submitted the ticket with.  After that, search for their first and last name.

5.  Product in Question is a good starting point, but it's a good idea to double check with the user if there is any question or if their account reflects licenses in both versions

6.  Operating System will be your best friend when getting tickets about crashing or color changes.  Some issues with the software are OS specific, such as color differences on Macs and crashing on PCs.

7.  Public Replies will be sent to the user as a reply

8.  Internal Notes will make the test area yellow and are only viewed by support staff when opening the ticket

9.  Time Submitted is just nice to know

10. Macros are accessed here.  More information about those are here

11. Submit the ticket as New, Open, Pending, or Solved depending on if you expect a response.