CS6 is unsupported on El Capitan.
The only possible thing to try is turning of the autohide menu bars in the system preferences.
Beyond that, you are on your own as CS6 has reached end of life.
Unfortunately for you, InDesign CS6 is never going to be updated. It's now four years old, and there are problems running El Capitan which will never be fixed. These issues are posted on this forum every day.
You can roll back to an earlier Mac OS X operating system, or get a subscription to InDesign CC.
ok thanks...should I just revert back to yosemite?
That would be the best course of action, yes.