How do you put GUIs above blocks/characters like the health bar/name for example?

Like in some games people have put an NPC's health displayed above their head, or they have the name of an NPC above it.

If you mean a health bar over people such as us players, here is how it works.

You must have a Model. inside the model, there must be a brick named Head (this is where the Health bar and name will be)

Now, Insert a humanoid. You will see that the name of the model is Model. To change this, simply change the name of the model. if you want it to have more health, you can just change the Maxhealth. Or if you simply don't want the health bar, just put maxhealth to 0. I hope this helps you.

Workspace Inside here is the Model Inside the Model is the Head and the Humanoid

All you need to do is put a health GUI into a billboard GUI, make it connect to the head, set the offset until it's above their head, and then wall la, you have a GUI above a character's or object's head. Though of course, it might take some optimizing to do that. Other wise, you might see your own health on their health bar,