You need to tip-toe through all CC versions to always save one version back and save a CS6 file from the original CC 2013 version.
This page explains what Mylenium says in more detail: opening After Effects projects from previous versions and saving back to previous versions
Basically, you'll need to save as CC (AE version 12) then open it in AE version 12 and save it as CS6.
Thank you for your response! But does that mean If i already updated my After effects to 2014 there is no way to save my Files for cs6?
But does that mean If i already updated my After effects to 2014 there is no way to save my Files for cs6?
It doesn't mean that at all!
One of the huge benefits of the Creative Cloud is that you can install any/all versions of AE you would like - all the way back to CS6! Here's how: How to Find and Install Previous Version of Adobe Apps in CC 2015
At my machine in my home studio, I have CS5 (which is the oldest version I bought outright), then CS6, CC, CC 2014, and CC 2015 all installed through the Creative Cloud. All are running with no problem. In fact, I jumped through all four versions just the other day in testing compatibility for someone who had a question on Reddit.
It's great! All you have to do is make sure that, when you do updates to CC 2015, you make sure you don't let it remove old versions (which it defaults to do which is DUMB). See here: keeping previous versions installed when installing CC 2015 applications