Need help with Reebok Precision XT heart rate monitor

My sister gave me her heart rate monitor , it is a Reebok Precision XT with a chest strap and it doesn't have instructions and I can't find anything on the internet to look up instructions or whatever and she doesn't remember how to us it and I have tried to mess around with it a few times to see how it works and I just can't figure the darn thing out. Does anyone out there have this one? if so could you please give me some basic instructions for using it.....thanks in advance