Mery,
The LEDs on the various IFI devices mean a variety of different things. The best thing is for you to download the manuals from the IFI website so you have them handy for reference. The LEDs also assist with calibration.
The robotics website is
http://www.ifirobotics.com/
I highly recommend you download to your computeer all manuals so you can refer to them during the competition season.