Hi! Thanks for the help!
I think that I am almost there, but nothing yet!!!

I am trying to use attachMovie (I use Flash 5).
The situation is that I want to have a MC with an animation (just like something sliding from left to right). But this "something" will be changed from times to times.

Well, I made this animation with a "nothing" sliding from left to right. This "nothing" is a MC with just one blank frame. Then I am trying to instantiate another MC inside that.

I put in the first frame of the main timeline the following code:

empty1.attachMovie ("pic","pic1",1);
empty1.pic1._x = 100;
empty1.pic1._y = 100;

PS: pic is exported through "linkage" option.

Nothing happens!!!