creating Dynamic textBoxes

Surround it with a loop. For example, if you want ten text boxes:

for (int i = 1; i <= 10; i++)
    {
    TextBox box = new TextBox();
    box.Text = "aa" + i.ToString();
    box.ID = i.ToString();
    form1.Controls.Add(box);
    }

But you should really, really be doing this within the form1 class and instance - not outside it. Let a class take care of it's own content!