HELP SPL millitronic

Hi guys , I was wondering if someone could help me with my project. I’m new to Arduino and would like to work on creating a system using Arduino Yun to read data from SPL Millitronic controller via RS232 and when the level of the silo reach low level send an e-mail to re-order.
I have no idea where to start. I have already bought the Yun.

Let me know if this is possible.