Referencing an .mc

i have a main timeline with an .mc. named
on this main timeline i have another .mc named mainContent_mc inside which i have placed some actions.

im not sure how to correctly call them. im trying to make each .mc interact or animate with eachother but i cant even corectly measure or work with them (the appears at one position on the stage and correctly alligned, but when i test it, the same is maybe 30-80px off position.

i have included the .fla so you might see, but really maybe need tute to show me the way, if only i knew what the name of the tute might be …so does anyone know what it is i need to understand cos im up against it now.

(for anyone who checks the .fla : i want to animate the ztop / zbot .mcs across the mainContent_mc, but at the moment cant do it)