minIMU-9 Project

So i get to program the AHRS visualization on python by connecting the arduino environment. as i get all the instruction from GitHub - pololu/minimu-9-ahrs-arduino: Arduino program for building an AHRS with a Pololu MinIMU-9
now i wondering how to add statement in the arduino sketch to program an if statement. For my case, i want to program the LED to light up if the roll angle is above 45 and below -45 . i hope someone can help me .

i put up the sketch here .

MinIMU9AHRS.ino (6.27 KB)