How to play movieclip that has been loaded into a sprite?(also external file import)?

I tried just using the gotoAndPlay method on the sprite, but it gives me an error. How do i go about correctly doing this?

What i am trying to do is load a character into separate sections via sprites within one main sprite, so when i click one button, it will play one sprite (the arms or feet for example), while still enabling me to perform a second movement with a separate part of the body at the same time if i press a different button.

the reason i am telling you this is because i also want to know how i could import one ‘character’, its movements, image files, etc. from an external file, so in the primary as3 file i could still trigger its movements after simply importing the characters file.

Any help, links, suggestions would be great. thanks.