need help creating a health system in my unity3D game

I am new to unity and i was wondering if anyone could give me the scripts on how to make a health syetem and what i would use each script on. thank you

I also have a question, Does anyone have a picture of 3 hearts 2 hearts and 1 heart that i could use to make kinda a health bar but every time he gets hit a heart goes away. I would make this myself but i do not own adobe photoshop