You can view all classes input in the TMS for your organization(s), by default, the Find Classes search is set to find all future classes for your organization(s). This means if the class is going to start in one minute or 5 weeks, the class will show in the search results. However, if the class has started already it is considered to be in progress or started in the past. Because of this, you need to search for it differently.
To find a class that is in session, go to Site Administration on the Classes tile, click the Find Classes link. This opens up the Find Classes page. Choose an appropriate filter to apply to your search. For instance, the Starts filter can be set to Today or Yesterday; or can be set to Exactly or Within the Last along with a calendar to choose the date. Alternately, you can search for classes that are in session by adding the filter called In Progress Now; to use this you will need to remove the Starts filter. Add the filter you want and click Search. You may add output options to view additional data in columns in the search results; after selecting/deselecting output options, click Search to display the new results.
In the results, click the class Name for the class you want. This will open the Class page to view details.