To add a class to My Queue, follow these steps:
Go to the video page of the class you want to add to your queue. Below the video player, click the + Queue button. There is also an x in the upper right corner of each video in your playlists if you wish to remove a video.
To view your queue, go to My Playlist > My Playlist > My Queue.
In this view, you can change the order of the classes in the playlist by clicking the Re-Order This List button.
Finding My Queue on Mobile
In the menu, go to My Videos > My Queue.