Since there are only two AE CC versions, it's easy: File>Save as Adobe CC... or whatever it says.
If you mean, "I want to save in AE CS6", that's a different matter: backsave in AE CC. Open the project in AE CC. Backsave to CS6. Pray that you haven't used any features from the more recent versions -- they won't be there.
And if you're giving the CC project file to someone else, know that they are renting AE CC 2014 in addition to AE CC, they have access to it, and can install it. No backsaving needed.
Thank you for answering my question.
but at the moment I want to save un AE Cs6 it won't give me the option for saving in AE CS6
Read more carefully: you backsave to AE CC.. You use AE CC to open the project file. Then you use AE CC to badcksave to CS6. You need AE CC to complete the process.