Hover over gui.button from script

Hello, I am new to 4.6 GUI system and I am trying to make my own inventory script, but i can not find a way to hover over these GUI.Button so they will show description of items. I have seen how to do it when you add new button to the scene, before playing the scene, but i dont know how to do it in runtime.

If all you want is to know when you have a mouse hovering over your button, put this function in a script on the button

void OnMouseOver(){
//DoStuff here
}