You don't have to do anything special to throw it away. There are not any hazardous materials.
If you have info on it that you don't want others to have- burn it. smash it, grind it up, and run some magnets over it.
Honestly I don't think anyone will be digging through your trash and then try to get the info off of a failed HD, unless you're the guy on Prison Break. It couldn't hurt beating it up a little though.
Have Fun! 🙂