Help needed with javascript

I need some help with some java script. I will now describe the problem.

I’m currently developing my own theme. I arrived at the editing of comments.php al ids are the standard ones.

I would like to know how can i add a 3rd permanent state to the input / textarea fields. I only have a input field where i aded by CSS a background image that has written on it: NAME: this is for the people that would like to comment, where they should write the name. Now when i select the field to type in it i’ve made the css hide the background that has NAME: written on it, so the user can type without having to see the background. Now here is where my problem is. After i typed something in that field, the background with NAME: written on it returns, setting itself behind the text just written in the input field, this is not very pleasent for the eye.

Does anybody have an ideea on how to set a 3rd state after somebody has written something in the field. i’d like that state to be with no background.