I need that when i click a button to open a popup text box(something like the box used for images) , and i need to use it whith php , to put it in php code so i can put it to show me a php string that i extract it from DB.

I have no experience with that kind of things , please help.

Use alert(string) box to pop up messages at any time you want inside javascript. It is one of the easiest way to debug. Though, do not attempt to use the alert() inside a loop without a condition for it, or you would keep getting the pop up that easily annoys you.