Help with Navigation

Ok Guys,

Here is my problem. I am building a three tier navigation system. I have my main menu and two empty movie clips to load the sub navigation into. What I want to happen is when I click on a button on the main menu to open up the first sub menu, I want the button to remain highlighted until another button in the main menu is clicked to show which area you are currently in. Similarly I want the same thing to happen when you click an option on the first sub menu to open up the final tier of navigation. Seems like it would be failry simple code. Im no as guru by any means…obviously!

an example:
Click on Portfolio
Click on Illustration
Click on Drawing2

(main menu)…(sub menu 1)…(sub menu 2)

news…
bio…
portfolio…Print…
…Web
Illustration…Drawing1
Drawing2
…Drawing3

Bonus Points:
I would like to make both intro and exit transitions between these stats as well. Any ideas?

Thank you for looking!
James