@Rohit_809 Kumar - 

Check out the Docs in the following link.  One needs to be logged into the FN Platform to see the Docs.
https://fwd.app/docs/enterprise/getting_started/configure_collection/devices/custom_commands/

There is a Fortinet example here:

That should get you started.  There are quite a few examples of parsing Custom Commands in the Community.  Let us know if you get stuck or have additional questions.  Note that one needs to run a Snapshot to execute the Custom Commands.

Thanks @RobertWelch  for the response , i added the command same way , but not getting output against them

@Rohit_809 Kumar - Let me see if I can mock this up a bit later today and create a bit more detailed response on how to approach this.