How to make a Fly GUI?

Please be more clear with your question. Also, please make an attempt at a solution to your problem. We know neither what you want nor to what extend you've gone to try to create the item you're looking for. Therefore, we cannot help you here. This is a place to ask for help debugging your scripts that you attempt to make, not asking for others to create something FOR you.

Please read this blog post to learn more on how to get the help you need.

If you don't even know where to start, please make sure you provide a clear explanation to what you're looking for. A "Fly GUI" doesn't cut it for a description. Are you looking for a GUI to control a plane model? Are you looking for a GUI that flies around the screen randomly? As an extension to the previous question, are you making a game where you click on images of the fly insect to smash them and earn points? We have no idea what you want, and you will likely get zero help unless you explain more clearly what you need help with.