First part of my Code.

Just started to write my code. With the following code I have made the trolley move from side to side of the screen. I still  have to put restrictions on the screen, so the Trolley will not go past a certain point.
Here it is --->

import flash.events.KeyboardEvent;
import flash.events.Event;

stop();
stage.focus = this;

var isRightKeyPressed:Boolean = false;
var isLeftKeyPressed:Boolean = false;
const TROLLEY_SPEED:Number = 8;

stage.addEventListener(KeyboardEvent.KEY_DOWN, isKeyPressed);
stage.addEventListener(KeyboardEvent.KEY_UP, isKeyReleased);
stage.addEventListener(Event.ENTER_FRAME, gameLoop);

function gameLoop(event:Event):void
{
moveTrolley();
}

function isKeyPressed(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
isRightKeyPressed = true;
}
if(event.keyCode == Keyboard.LEFT)
{
isLeftKeyPressed = true;
}
}

function isKeyReleased(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
isRightKeyPressed = false;
}
if(event.keyCode == Keyboard.LEFT)
{
isLeftKeyPressed = false;
}
}

function moveTrolley():void
{
if(isRightKeyPressed == true)
{
trolley_mc.x += TROLLEY_SPEED;
}
if(isLeftKeyPressed == true)
{
trolley_mc.x -= TROLLEY_SPEED;
}
}

 I have also used the following code to make my Home Screen compatible, with 2 buttons (the Play button and the Instructions button)
Heres that code -->

import flash.events.MouseEvent;

stop ();

start_btn.addEventListener(MouseEvent.CLICK, startBtnClicked);
instructions_btn.addEventListener(MouseEvent.CLICK, instructionsBtnClicked);

function startBtnClicked(event:MouseEvent):void{

gotoAndStop(4);}

function instructionsBtnClicked(event:MouseEvent):void
{
gotoAndStop(3);
}