CS6 is a paid version upgrade. It can be purchased as a perpetual license product from Adobe, or you can get it as part of a subscription to Creative Cloud. Creative cloud is now two versions advanced beyond CS6 (and CS6 cannot open CC or CC2014 files).
The subscription model allows you to always have the most current versions of Adobe software without additional upgrade costs, but you pay a monthly fee, and if you stop your software will become unusable.
Thanks Peter but if I don´t want to subscribe to Creative Cloud, where can I find the CS6 upgrade? (I have been looking through the site but it´s not very clear)
Just to repeat what you’ve already been told. You are affectively buying a version that is already two versions out of date. There’s very little benefit of going from CS5.5 to CS6 at this point.