How to add an object on mouse click?

You could create the movieclip object and put it in the library with a linkage name, e.g. mcExample and then on the main _root. timeline add something like:

this.onMouseDown = function(){ mcExample = this.attachMovie("mcExample", "mcExample", 1); }

This attaches the movieclip from the library onto the stage when the left mouse button is pressed. You can then manipulate the movieclip like any other using its identifier: mcExample. If you want to change the name of the attached movieclip then change the second parameter of attachMovie