You can submit a ticket by pressing the tab "submit a ticket". Then you need to select a department you want to submit your ticket too.

When that is done, you will be met with a form that you need to fill out.

You have now submitted your ticket!

To reply to one of your tickets, you need to locate your ticket in the list and click on it.

Then in the bottom you will find a reply form, where you will have the possibility to reply to the ticket you submitted.