How do I fade out a song?

Hi,
I know this must be a dumb question , but I'm new to all of this and I can't figure out how to fade out the end of a song. I see "Toggle region fade in" and other fade items in the menu, but i don't know where to start. Is there a way to select the portion to fade out and give it some kind of command? I'm learning this little by little.
Jimmy