I highly recommend you reading my tutorial on Shooting Bullets before beginning this tutorial, as I will create this code by adding on to the code found in that tutorial.
Let's begin by creating a new Flash file in AS2, or better yet just using the file you made in Shooting Bullets.

This time believe it or not we are only setting 1 new variable:

var bullet_array:Array = new Array();

Add this to the top of your script.

And here is an example of what the final product will look like. Use the arrow keys and spacebar to rotate and fire.