Ive been doing a little research for my audio CD on how people learn how to sing. I have always taken lesson and mixed that with my own research and audio CD's that i can practice to in the car.
This site gave basic information on how to learn and it is a good starting point for anybody or even a refresher.http://www.wikihow.com/Learn-to-Sing
I also came across this article, i found it pretty funny as i sing in the car all the time, it is probably where i practice the most. http://thoughtcatalog.com/kelsey-hayes/2013/12/singing-in-the-car-is-all-the-therapy-you-need/
there is also reference to the film step brothers where all the kids and the mum and dad are singing sweet child of mine in harmony after taking singing lesson... well worth a watch