easy. just say:
attachMovie ("whatever", 1);
that means that you import a movieclip from the library to the stage. BUT: you need to make the MC (movieclip) exportable for AS (actionscript).
how to? just right-click the symbol in the library and select linkage. then export for actionscript. then you need to name it (standard: the real MC name)
in this case i have a MC called "whatever".
so when you attach the movieclip to the stage it's coordinates will be 0, 0.
now you can set the coordinates as you want. i hope you know how this works.
the good thing on importing the MC to the stage: you can say:
whatever.removeMovieClip();
and it disappears! :D
got it?