With so many brands and types of calculators available these days, it is for all practical purposes impossible to create a single tutorial that can assist every student in using their calculators. That having been said, most calculators these days are either made by Texas Instruments or Casio. Both of these companies have training materials available for students interested in learning more about their calculators.
If you use a Texas Instruments calculator (TI-30, TI-34, TI-83, TI-84...) then the below link will take you to their tutorial page. There you will find links to numerous quality videos for every calculator they make. Below that you will find a link to a video giving you a quick tour of their website.
If you use a Casio calculator (FX-55, FX-115, FX-200, FX-260, FX-300, FX-9860, FX-9750...) then the below link will take you to their product page where you can get access to copies of user manuals and their FAQ's pages. Below that you will find a link to a video giving you a quick tour of their website.