...start by making a single square

  Create a couple of empty movie clips to hold the elements...
    ...first clip is used to hold all the elements in the scene:

... I centre it on the stage so that the elements inside can use 0,0 for the screen centre
(the stage size is 600x300):

...then create a movie clip called 'sq' inside 'drawing' clip.
This clip will contain a single white square:
  Draw a white filled square - size 4x4 origin in its centre


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...