I made a quick video on Sarge's request for information on musical tongue techniques.
It's kind of an amateur and chopped up affair but I think It will be plain enough. These may or may not be useful to you but they are good to have in your bag of tricks..lol!
Can you make a motorboat sound with your tongue? That's the trill that you are looking for! This ability will equally translate into your study of Spanish and other languages. (Hint. You may have had the ability all along and didn't recognize it!)