For example: If you click on a GUI button it makes a sound like FX or music.
You'll need to have a sound inside the localscript, then if you put a localscript inside a GUI it should look something like this:
script.Parent.MouseButton1Click:connect(function() script.Sound:Play() end
This basically just makes it so when you click the button a sound that you choose will play. Hope this script helps you, and others.