For generic step by step instruction on configuring data collection and notification, you can read this tutorial: http://wiki.netxms.org/wiki/How_to_send_e-mail_notification_when_disk_space_is_low. You only will need to change parameter you are monitoring. For monitoring new files in directory, you can use parameter File.Count, like this:

File.Count(/tmp)

will get total number of files in /tmp directory. If you need count files by mask, you can add pattern as second argument, like this:

File.Count(/tmp,ssh*)

will get number of files with names starting with "ssh" in /tmp directory.

Best regards,
Victor

I want create new one for the if the folder add new file show me message  (For Agent)

what is the method for the data collection

and the show message for the Thresholds

example :  like if the node down they show me message (For Agent)

thanks a lot for help me.

There is a separate section in manual dedicated to data collection: https://www.netxms.org/documentation/adminguide/data-collection.html. Please read it first and feel free to ask any specific questions not covered in the manual.

Best regards,
Victor