Applications can be found in the scene's main page in the "Applications" box. 

Choose the required application by clicking on its name and then you will be able to see the options that it holds.  

Here you can choose one or more options (it depends on the settings of the application) and then press the "Application" button. Now you have applied for the group of your choice. 

Modify your application

If the group that you have previously applied for does not suit you, and you would like to change your choice, then - if the settings allow it - you can modify or delete your application with the "Modify application" and "Delete application" buttons.