This video will show you how. Written instructions with pictures are provided below the video.
Click the Change button for Course Status.
Select the box next to the Open & Full w/Waitlist Open option. Click Save.
Note: If the class is showing that it is closed with seats available, instead select the Open & Full option.
Select the class of your choice. Click the Generate Schedules button. Next, click View.
Click Send to Shopping Cart.
Check the Wait List box if you would like to be on this class wait list.