Hi!
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
