Hi sirgascone and welcome.
Well done for trying to learn and actually reading the help file!!!
You asked a very important question, how to determine whether a horse's price is drifting. You need to formulate the criteria for that with simple words before taking them to the trigger conditions. Once you have a clear idea, I'm sure programming it into the triggers will be a matter of minutes, and we're here ready to help.
So try to just write it down as if you were explaining it to a broker or someone ready to make a bet for you. The "drifting" and "steaming" can represent different concepts for each traded, so come up with your own.