c# - how can i call a method using button -

i have simple question:i have example

public int x(int a,int b) { } 

now how can call when click button?i mean when click button,x() call , work,thanks helps

private void button1_click(object sender, eventargs e) {    int retval = x(1,2); } 

or if part of class

public class foo {     public int x(int a, int b)     {         return + b;     } } 

then like

private void button1_click(object sender, eventargs e) {     int retval = new foo().x(1, 2);     //or     foo foo = new foo();     int retval2 = foo.x(1, 2); } 

or if static member

public class foo {     public static int x(int a, int b)     {         return + b;     } } 

then like

private void button1_click(object sender, eventargs e) {     int retval = foo.x(1, 2); }