Implement ALE_RESERVATION_CREATE

Hi;

I want to trigger the generation of the IDOC MRESCR after the save the reservation MB21/MB22 transaction. To do this, they advised me to use the standard module function ALE_RESERVATION_CREATE .

In what program I need to implement this?

I want to report that, I am a young novice in ALE/IDOC and the additional setup is already perform, still me have this step. An example of implementation help me enormously to advance the project.  

Thanks in advance for your help.