Easy Preloader Bar!

First, open flash, and make a New file. Now, click the rectangle tool (or press R on your keyboard), and draw a textbox.

Next, just click the middle, or the fill of the new rectangle, and right click, and go down to Convert To Symbol. Then, make sure to assign the Instance Name of the box:
bar.

Now, read this carefully, unless you want your loader bar to load from the middle to the sides! Double Click on the bar movie clip. In the middle of the clip, there should be a small cross, surrounded by a cirlce. Move the bar so that that specific cross is on top of the left side of the bar. In doing this, the loader bar will load from the left to right, instead of from the middle out. Make sure to do that! After you have done that, double click on the bar again, to get back to the Scene.

This next part is optional!

Click the text tool (or press T on your keyboard). Adjust the font to what you want it to be, and size, and type in Loading... Remember, this part is completely optional!

This next part is manditory for a perfected, working preloader bar!

On your keyboard (if you have a Windows) press F6. If you don't have a Windows, then right click on Frame 2 on your timeline, and click Insert Keyframe.

On this Frame, on the Timeline at the top, right click again, and go down to Actions, and click. Add this action to the Frame:

gotoAndPlay(1);

Once you have done that, go back to the first frame, with the preloader bar and add the following actionscript:

stop();
loadpercent = _root.getBytesLoaded() / _root.getBytesTotal * 100;
if(loadpercent != 100){
setProperty(bar, _xscale, loadpercent);
}else{
gotoAndStop(3);
}

Now, for the very last part!! Go back to your timeline, and right click. This time, go down to Insert Blank KeyFrame. On this Frame, add anything you want! Text, a picture, a movie, whatever you please!