How Can I Display The Data In Textbox

protected void btnShow_Click(object sender, EventArgs e)
        {
            string conStr = ConfigurationManager.ConnectionStrings["CStringCRM"].ToString();

            DataTable dt = new DataTable();
            SqlDataReader dr = null;

            using (SqlConnection conn = new SqlConnection(conStr))
            {
                // Creating insert statement
                string sql = string.Format(@"SELECT * FROM UserInfo");
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = sql;
                cmd.CommandType = CommandType.Text;
                conn.Open();

                dr = cmd.ExecuteReader();

                dt.Load(dr);

                conn.Close();
                cmd = null;

            }

            GView.DataSource = dt;
            GView.DataBind();

            txtFName.Text = dr["UFName"].ToString();
                       
        }