Buttons' problem..experts please help

The case is basically like this:

I got 2 buttons, I named it button1 and button2.

The effect I want is like this, when mouseoever button1, the size of the button will become bigger, while mouseout, the button’s size will remain in normal condition(smaller size). When I click over button1, the size will become bigger and remain static in bigger size button condition.

Then when I mouseover button2, same effect, which is the size of button2 bcomes bigger, and mouseout, the size will change back to normal size. When I click on button2, the size will remain static is bigger size, but button1 will be changed from bigger to smaller.

Here is the example, http://www.templatemonster.com/website-templates/12970.html

Can anyone help…many thanks…

ps: as long as it works, regardless what effect for the button, either color been changed, or button size bcomes bigger…