Dexcom question from new user

I just started on the Dexcom on Wednesday and things are going as I had expected them to. Some of the readings are spot on with my finger sticks and some readings are about 20 - 40 points above or below the finger sticks with on glucose meter.

I wanted to know if any of you calibrate the Dexcom more than every 12 hours? And can anyone help me understand the Dexcom data manager program and how to best use the data to perfect my pump settings? I didn’t receive any kind of instruction manual with the software program that would explain how to use the Dexcom data manager program.

Shirley from Georgia
Type 1.5 since June 2005
Animas 1250 since June 2006
Dexcom cgm since June 2008