How do i refer to this textbox if it dosnt exist yet?

Hi, i am creating this button where when you click it creates a new textbox under the last one, is it to save dates and stuff like that, but i am having a problem refering to saving the txtbox.text since i dont know how to refer to it.

 

Here is the code:

 

int tb = 0;

private void button12_Click_1(object sender, EventArgs e)

{

TextBox ls = new TextBox();

string tB = tb.ToString();

int t = 0;

File.Create("fechas" + tB + ".txt");

ls.Name = "ls" + tB;

ls.Location = new Point(textBox1.Location.X, textBox3.Location.Y + t);

ls.Multiline = true;

ls.BorderStyle = textBox3.BorderStyle;

ls.Size = textBox3.Size;

ls.BackColor = textBox3.BackColor;

this.Controls.Add(ls);

textBox3.Location = new Point(textBox3.Location.X, textBox3.Location.Y + 50);

button12.Location = new Point(button12.Location.X, button12.Location.Y + 50);

t = t + 50;

}

 

I highlighted in yellow what i have wrong, do some one know how to refer to the textbox.text and at the same time changing the name that you are refering to.

Thanks for reading, i will be looking forward for your answers.