You can compare the queue with drawing a number at the local bakery: You as a person get a specific place in the queue.
The queue opens automatically when the sale starts. With your mobile number and e-mail address you can join the queue. Make sure you use the mobile number and e-mail address which you will use to buy your tickets. If you made a mistake in either one, you can not buy tickets. So check the data you specify on (spelling) mistakes!
If you are in a queue for multiple events, you can specify your favorite theater or preferred date while waiting. You will receive live feedback about your chance to get tickets.