How to reverse Cmd-Z ?

Hi everyone,

I know this is a simple question but I cannot figure it out as I am afraid pressing the wrong button will mess up what I currently have on my sequence.

I use a lot of Cmd-Z to undo what I do not like. The problem is that very often I press Cmd-Z too many times, so I want to get back what I undo.

Would appreciate if someone can teach me how do I do that ?

Thanks