Additional information about Visual Basic 2015 and procedures

Hi!
I would like to know more about Visual Basic. What are the two types of procedures in this language? Can you show me how to create function using general declaration? What are the uses of Sub? Sub-name? What are arguments or parameters? How to pass arguments in sub-procedures and functions? What do you mean by return value? What is the uses of Private and Public for this? Can you show me how to implement the sub-procedures?
Thank you!
