Action script question, please answer quickly

i have a question. in action script, how do i make a text button turn into another object on mouse over? i want to make a button turn into a square or get bold, how do i do that?

please use in-depth explanation

Shape tween.

Draw text in Frame 1. Hit ctrl+B twice to break the text apart into fills.

On frame 10 (in this example it will be 10 frames, do whatever you want) right click and choose “Insert Blank Keyframe”

Draw your square in the same spot you did your text.

Right click on the grey area linking the two keyframes.

Choose “Insert Motion Tween”. The area will turn purple.

Hit CTRL+F3 to open the Properties panel.

There will be a drop down box that says “Motion” click that and choose “Shape”

Your purple area will now turn into a green area with a line and an arrow pointing to the keyframe in frame 10.

Test your movie and it should work.