Zelda like HP? [RMXP]

[Kiloku]

I want to have a zelda like HP Gauge (hearts), i already made the pictures, but i can't find something to make the condition for the images to appear be "Hero HP=91% to 100%". If you didn't get what i mean, tell me where exactly you didn't understand, please

[Twar3Draconis]

Variables.

Or script the whole thing out, it's less laggy and can handle more complex functions.
Although, I think there is a script for this.

[Kiloku]

I can't script, and i tried variables, i'll try something a friend taught me about variables 2day