How do I add for a GUI button to give me a certain potion effect if that button is pressed from the GUI menu?

I am trying to add an element in the game where from the GUI you press one of the buttons it gives you an effect? Ik how to use potion effect but don't know how to do it when a player uses the item, choose from the button and gets that effect.
 

If player press GUI button 1.do player get's health boost

I need help to code something like this