"Tells my what to think" it's a common idiom in English, meaning not just that you were
told", but that you were commanded and followed*. It's basically synonymous with "controls how I think", and almost always used as a negation. That is, someone will say "he doesn't tel me what to think" to express that their thoughts are still their own and independent.
In that context, "The media doesn't tell you what to think, it tells you what to think about" is meant to be taken as "The media doesn't control how you think, but it defines the discussion." I think this is just a case where an author decided for alliteration over clarity. Sometimes that's a useful path, as alliteration can help phrases stick in the social consciousness. In this case it's just confusing.