ARDUINO UNO + DFROBOT RS485 SHIELD + OMNICOMM FUEL SENSOR RS485

Hi guys

at this time I want to start a project to measure the fuel sensors Omnicom 2 LLS20230. Which use EIA 485 as connection and have a message format itself.
This I want to do with ARDUINO UNO and Shield DFRobot RS485.

The problem is I have no idea how to start as this type of communication is new to me.

Would greatly appreciate if someone could give me a hand.
these are the datasheets:

http://www.omnicomm-online.com/downloads/Datasheets/Datasheet%20Fuel%20level%20sensor%20LLS%2020230%20v2.13.pdf

http://www.dfrobot.com/wiki/index.php/RS485_Shield

Thanks in advance for any help

Somebody help me please....

a little help please