When you create a new RDML function and specify a new function type of 1 (Generate from an Application Template) then the Application Template Facility will be invoked.
The Application Template Facility will initially place a "pop-up" window over the lower portion of the screen that you are currently using.
This pop up window is displaying a list of available Application Templates. From this pop up window you can elect to:
There is not a lot more that can be said about using Application Templates, because they are most often site defined, and even those that are shipped with the product have probably been modified to match your site's exact requirements.
However, some tips in using them are as follows: