<<  
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...duplicate the square in random positions
   
  Before duplicating, hide the master square off the stage...
    Hide the initial square by giving it a y position way off the stage...
_root.drawing.sq._y=1000;
 
  Now duplicate this master square 198 times in random positions...
   

This next part of the script is a loop which creates an object with random _x and _y values, then uses this initialise object when duplicating the 'sq' movie clip. This means each new copy appears in a random position on the screen:
for ( i = 2; i < 200; i++ )
{
    initOb={ _x:random( 600 ) - 300, _y:random( 300 ) - 150 };
    _root.drawing.sq.duplicateMovieClip("s" + i, i, initOb);
}
...after these lines, the scene will contain 198 white squares (the original is not in view)
   the squares have the instance names 's2', 's3', 's4', ... ... 's199'.
  ( -total number of lines (excluding brackets) is 15)

open raw text script...
paste the script into the first frame of an empty flash file (set script window to expert mode first),
The stage should be 600x300 with a dark background...