This settings is for incoming email. That means it will check incoming email. If get any email then it will convert that into ticket. So you have to put imap information of your mail server. In the right site of this window you will get information for IMAP.
You have to a cron job ( Scheduler) . The cron job command will be in the box name Cron Job Comand ( Red 1 number circle in the image). Please add this command into a short interval in you server cron job list