How to use YesNo Cancel message box.

Question

1.I want do something when user Click on Yes.

 

if(Yes) 

{

messageBox.Show("Yes Clicked."); 

}

else if(No) 

{

messageBox.Show("NoClicked."); 

}else{

messageBox.Show("CancelClicked.");

 

} 

 

2. Help me for above