first thing to make sure is that your cas 2 is not a clone. see below and attached picture. then if it is not a clone download the cas studio 6.1 from duolabs or if it is a clone download the cas studio 5(i can email this to you if you need it). this software is really easy to use and there are plenty of how to threads elsewhere on this fourm.
How to tell difference:
Look underneath the cas2 - there is an indented square area in the middle (as though there should be a sticker there) If this indented area has a double line top and bottom that would indicate a fake.
Also looking from underneath through the plastic casing.- where the cam is inserted you should see three plastic struts that balance the cam - one near the middle of the slot, two at the edges. If these are missing it is a fake.
If you have a fake DO NOT LOAD CAS STDUIO 6!!! This contains code that WILL kill your Cas 2 with NO PRIOR WARNING. After the event the software will tell you that they just killed your CAS2
Duolabs admit their Cas Studio 6 will kill some original CAS2 as well. In this case they ask you post it to Italy where they will repair it and send it back with a "free gift" - Do you really want the hassle???
If you stick to the perfectly working earlier verisons of cas studio you will be fine.