Help Converting simple game from AS2 to AS3

I need help updating a previous game project from AS2 to AS3.

I have never actually used AS3 (have not used flash in many years). If someone could convert this code and explain a little I would be very grateful.

Even if someone could convert the could Im sure I will understand the changes by looking.

// Params

var bulletSpeed = 25;

var bulletSpread = 10;

var playerHealth = 25;

var enemyGeneration = 30;

var enemyMaxSpeed = 9;

var enemyMinSpeed = 1;

var enemyHealth = 10;

// Vars

var shots = [];

var enemies = [];

var kills = 0;

var RADIANS = Math.PI / 180;

var DEGREES = 180 / Math.PI;

// Init

player.health = playerHealth;

updateScore();

// Start game

onEnterFrame = game;

// Main game loop

function game(){

          updatePlayer();

          updateShots();

          updateEnemies();

}

// Update the player

function updatePlayer(){

          // Player mouse aim

          player._rotation = Math.atan2(_ymouse - player._y, _xmouse - player._x) * DEGREES;

          // Player shooting

          if(shooting){

                    shoot(player, player._rotation - (bulletSpread / 2) + random(bulletSpread), bulletSpeed);

          }

          // Update health bar with easing

          var percent = player.health / playerHealth;

          healthbar._xscale += ((percent * 100) - healthbar._xscale) * .5;

          var frame = 1 + int((healthbar._totalframes - 1) * percent);

          healthbar.gotoAndStop(frame);

          // Check if player died

          if(player.health <= 0){

                    healthbar._width = 0;

                    onEnterFrame = null;

                    // Game Over!

                    this.createTextField("diedText", getNextHighestDepth(), 0, Stage.height / 2 - 25, Stage.width, 76);

                    diedText.text = "GAME OVER.";

                    var tf = new TextFormat();

                    tf.color = 0xff0000;

                    tf.size = 50;

                    tf.font = "Arial";

                    tf.bold = true;

                    tf.align = "center";

                    diedText.setTextFormat(tf);

                    diedText.selectable = false;

          }

}

// Player mouse click tracking

function onMouseDown(){

          shooting = true;

}

function onMouseUp(){

          shooting = false;

}

// Create a new bullet

function shoot(origin, angle, velocity){

          var init = {

                    _x:origin._x,

                    _y:origin._y,

                    _rotation:angle,

                    xSpeed:velocity * Math.cos(angle * RADIANS),

                    ySpeed:velocity * Math.sin(angle * RADIANS)

          }

          var d = getNextHighestDepth();

          var shot = attachMovie("bullet", "bullet" + d, d, init);

          shots.push(shot);

}

// Update all the shots

function updateShots(){

          var i = shots.length, shot;

          while(i--){

                    shot = shots;

                    // Move the shot

                    shot._x += shot.xSpeed;

                    shot._y += shot.ySpeed;

                    // Check if shot went out of bounds

                    if(shot._x < 0 || shot._x > Stage.width

                    || shot._y < 0 || shot._y > Stage.height){

                              shots.splice(i, 1);

                              shot.removeMovieClip();

                              continue;

                    }

                    // Check if shot hit an enemy

                    var e = enemies.length, enemy;

                    while(e--){

                              enemy = enemies;

                              if(enemy.hitTest(shot)){

                                        enemy.health--;

                                        shots.splice(i, 1);

                                        shot.gotoAndPlay("die");

                                        break;

                              }

                    }

          }

}

// Update and generate enemies

function updateEnemies(){

          // Randomly generate new enemies along edge of screen

          if(random(enemyGeneration) == 0){

                    var d = getNextHighestDepth();

                    var enemy = attachMovie("enemy", "enemy" + d, d);

                    if(Math.random() < .5){

                              enemy._x = random(Stage.width);

                              enemy._y = Stage.height * random(2);

                    }else{

                              enemy._x = Stage.width * random(2);

                              enemy._y = random(Stage.height);

                    }

                    var angle = Math.atan2(player._y - enemy._y, player._x - enemy._x);

                    var speed = enemyMinSpeed + random(enemyMaxSpeed - enemyMinSpeed);

                    enemy.xSpeed = Math.cos(angle) * speed;

                    enemy.ySpeed = Math.sin(angle) * speed;

                    enemy.health = enemyHealth;

                    enemies.push(enemy);

          }

          // Move all enemies

          var i = enemies.length, enemy;

          while(i--){

                    enemy = enemies;

                    enemy._x += enemy.xSpeed;

                    enemy._y += enemy.ySpeed;

                    // Check if enemy has been killed

                    if(enemy.health <= 0){

                              enemies.splice(i, 1);

                              enemy.gotoAndPlay("die");

                              kills++;

                              updateScore();

                              continue;

                    }

                    // Check if enemy reached player

                    if(enemy.hitTest(player)){

                              enemies.splice(i, 1);

                              enemy.removeMovieClip();

                              player.health--;

                    }

          }

}

// Update the scoreboard

function updateScore(){

          score_txt.text = "Kills: " + kills;

          updateHighscore();

}

// Update the high score

function updateHighscore(){

          var so = SharedObject.getLocal("player");

          if(!so.data.highscore)

                    so.data.highscore = 0;

          if(kills > so.data.highscore)

                    so.data.highscore = kills;

          highscore_txt.text = "High Score: " + so.data.highscore;

}