How to track character positions in a TextBox?

Question

C++ / C#

Hi all.
I created 2 textboxes, and I need to make sure that the last time a character is entered in the first textbox, its position in the second textbox is displayed. To solve this problem, I need to understand how to track the position of a character, and I already know how to make an input.
Please explain to a newbie how to do position tracking.

Answer 1

protected void TextBox1_TextChanged(object sender, EventArgs e)
{
  if (!String.IsNullOrEmpty(textBox1.Text))
    textBox2.Text = textBox1.Text.IndexOf(textBox1.Text.Last()).ToString();
}

Answer 2

Take the length of the line -1 - the first textbox, add spaces in the 2nd to the length of the line of the 1st textbox. So it is possible?