As Psyco mentioned, if you can, come to the Training Arena and look for a trainer. There are many people in there who can help you out, plus a few people dedicated to answering questions or showing new players the basics.
I suspect you are expecting too much turn-rate and overcontrolling them. Some aircraft behave very poorly to being overcontrolled, spinning with little or no control. Generally, listen for the stall horn, a buzzing sound that warns of an approaching stall. If you can control how loud the buzzing sound is, then your stick is likely calibrated alright, you are simply trying too hard to turn.
Turn rate is also affected by altitude, speed, and weight, not to mention the differences between aircraft. Select an aircraft that is relatively easy to fly if you can, something like a Spitfire V, and don't overload it with excess fuel or bombs. You can do this offline or online and just get the feel for flying and being gentle on the controls. Also, it can take up to 2.5 minutes for an aircraft to achieve maximum speed, so don't be impatient. When too slow, you are more prone to stalls while at higher speeds you may be able to handle the controls a little more firm.
-Soda
AH Trainer
The Assassins.