Lets say I have a GUI in PlayerGui. It's enabled when the player sits in a chair (therefor, setting it to visible).
I want a part of the GUI to hover on a specific Model/Part on workspace. How would I do this?
As an example, Imagine the ROBLOX game watchdogs, when you click in a player, a GUI only you can see hovers that player and follows wherever he moves.
I think what you are looking for is called a BillboardGui. Take a look at the example at the link, and see if you can make something out of that (it helped me a lot).
It has already been said that since you didn't have any basis of code to provide, we can't actually fix anything, but I believe this should get you going.