You need to do that in run time.
Suppose you have a windows form, and for n you want to create n labels and textboxes.
Now you can do:
for (int i=0;i<n;i++){>
Label label =new Label(){ Text = "WHATEVER"};
Textbox textBox= new Textbox(){Text = ""};
yourForm.Controls.Add(label);
yourForm.Controls.Add(textBox);
}