How To Make an Event when Enter Key is Pressed in a TextBox in C#

First, you have to add a KeyPress event just like the picture show below.

private void txtUsername_KeyPress(object sender, KeyPressEventArgs e)

        {

            if (Convert.ToInt32(e.KeyChar) == 13)

            {

               //This is where you will put your code if Enter key is pressed

            }

        }