If this is a basic player health bar, I would suggest starting with this tutorial:
https://coronalabs.com/blog/2013/05/14/sprites-and-image-sheets-for-beginners/
Your sprite frames would be different increment levels.
If your health increases, say a player going up a level gets more hit points, and you need to show a relative scale (like say a percentage) instead of fixed increments, consider using a red rectangle with your hollow character setting on top of it and a mask the shape of your character applied to the red rectangle to hide the area outside the character. You can initially set the height to 0 for the rectangle and as you do damage, change the height to the amount that represents the current health. Say your person is 50px high, it might be: