Anyways, down to your tutorial. I'm assuming you have basic knowledge of actionscript for this. This is very simple, but since I have written each step in detail, it looks like a very big tutorial, so don't get scared by the length dude! On your marks, set, go...
Start up Flash, if you don't already have it started.
In your new document, create a new button symbol and name it butt1 or something.
Create all the frames - over, down and hit frames the way u normally would with a button (with some variation for the Over and Down frames)
Create a movie symbol and name it MainMenu.
In here, on the 1st layer, 1st frame place your button symbol (we will call this the Parent button).
Add a "stop" action on this first frame.
Insert a keyframe on the 5th frame.
Create a 2nd layer and insert a keyframe on the 5th frame again, this time of course on the 2nd layer.
Here, (on the 2nd layer, 5th frame) place copies of the button from the library the way you would want them to appear when the user's mouse is over the parent button. We will call these buttons "child buttons". Remember to place them as close to the parent button, or to one another as possible.
This frame should show the completed menu, ie. the Parent button alongwith the child buttons upon mouseover.
Next, right-click on each of these child buttons and from their Properties, select "Track as Menu Item".
Now create a new layer 3, and insert a keyframe on the 5th frame again.
Draw a square large enough to cover all the buttons on the stage.
Select it and press F8. That is to convert it to a symbol. Make it a button symbol and let's call this "Back", cos' that's what it will be doing.
Edit the button, and insert a keyframe only on the last frame. i.e the Hit frame. Delete the square and insert blank keyframes on the other three frames - Up, Over and Down . You should see a bluish square in the place of the square you just created.
Next return to the MainMenu movie clip.
Select the 3rd layer and drag it to the bottom of the lot. So the order would look like frame3, frame1, frame2.
Now select the Parent button on the 1st frame and insert this action: On RollOver, goTo frame 5 and stop.
Select the "Back" button (large square button) on the 5th frame, and insert this action: On RollOver, goTo frame 1 and stop.
That's all to it! Now place your MainMenu movieclip on your main stage and test it.
I am attaching the .fla file I used while typing this tutorial for your reference. Do drop me a line if you're still getting stuck somewhere.
All the best, and remember to get creative once you get the hang of this. Check this to see what I mean-
http://www.donboscomumbai.org/cookie/dubaigolf/index3.htm
There's humongous stuff u can do knowing how to manipulate menus... ;)