Help - Round Menu

Hi, I'm new to flash AS3.0, now I'm facing a problem of a round menu, which i expected to design as follows,

1. Separate a circle to 8 parts average parts as button in the main menu.

2. Make a circle rotation.

3. random to click any button in the circle, the movement will stop and pop up a content which face forward to the direction which same as the button.

4. After few seconds it will jump back to main menu again, and the circle will rotate again from the previous position.

I have done some thing as step 1-3, but i have no idea about step 4, very appreciate any genius can help me on this, thanks a lot!:)

PS. Please download my working file from this link:
http://wtrns.fr/sWQZDX3w7oWOIY

Thanks!