Hi Thirawad,
Can you be more specific about which part you're having trouble with?
The help in the SSH data source explains how to get SSH connectivity in a common Linux situation. You simply need to generate the keys, install the public key on the target machine, have the private key to gain SSH access on the Mango machine, and point the data source at this file.
Data points run commands and then take the response as their value. So, maybe you're grep'ing values from files into a numeric point. Maybe you're cat'ing a file into an alphanumeric point so that you can run a script over it.