If you watch the MOCP portal, you'll be able to view your usage over the next few days weeks. Then its just a matter of adding the rates in.
I also as a general rule recommend that anyone using the platform get a REALLY good handle on costs/pricing before they deploy something. Web Sites are 10 free (for now), the cloud service is approximately $0.12/hr per core (so it depends on the number of
instances and their sizes), and the storage account is how much data you have stored and how often its accessed. Plus there's bandwidth for anything that's sent out of the datacenter (this includes sending html/images/css/etc... back to anyone visiting your