paths in actionscript use dot syntax and you have words
_root, _parent, this to refer to timelines. _root always refers to
the main timeline. [however, you should avoid using _root because
... ok, you will see later on :) ]
so, if you have a button inside a movieclip and you want to
refer to that timeline on wich that is you simply can write:
try to play with these expressions a little bit since using
these is core knowledge in scripting.