When you go to the "Discover" page it lists upcoming live classes by default.
For example, you can see these are all classes coming up on March 9th, including one "In Progress".
You can also select a specific date that you want to find an upcoming class in the top sort menu:
If you are an LiL+ Member and want to see classes that are available to you. Make sure to choose "Membership" under the price sort: