Question about class

Question

Hi I need some help about C#

I know it is elementary but I don't know how to do that. and also I works without database

I have class User with

string name;

string lastname;

int years;

 

and then a metod insert ()

{

  User us=new User();

    name=textbox1.Text;

    lastname=textbox2.Text;

    years=textbox3.Text; 

} 

 Now for example I need to add(insert) tree(3) users and then write them in listbox, message box or something.

 

I hope I was clear enough and correctly ask the question

(How to read all instaces of the same class and also I need to sort them by year)