To export the tickets from your helpdesk, please navigate to the Tickets tab and choose the pre-existing 'All tickets' view from the ticket list page. You can then choose and apply all the necessary filters such as the created time, agents, groups etc on the right and then click on Export in the top right corner.
Once clicked on Export, another window pops-up and in here you can choose the format of the file along with desired ticket fields that should be included in the ticket export.
1) Please make sure that the time frame set on the ticket list page is greater than the time frame set in the Export window. It is recommended to set the Created time field as 'Any' in the list page and apply the desired time in the export window.
2) The description and other multi-line text fields can also be included in the Export by clicking on 'Show multiline text fields'.