Change and update TextBox value based on DropDownList Selected value in ASP.Net

I have one dropdown list and two textbox.

i am developing a small application for my par tics in which currency name  populate from the data base which are in drop down it will working now.

Now I want when I select currency name from dropdown list the code the and the country name show in the  other textbox value .for example when I select Currency name like UK pound the value show .one show currency code 2 and other country name United state. All text box  value change on changing vale in droupdownlist dynamically means all value dependent on the dropdown list .

All value from the data base  

I  bind three value with the currency name ,id,currency code and country name. because when I change the dropdown list so change value in text box .but I fail to do that.

Please help me how value change in textbox to changing value in dropdown list. I know code show be on the DropDownList1_SelectedIndexChanged but I have no exact code

My data base.table 
Id (primary key)	Currency Name	Curreny code	countyname
1	          Bangla Taka	3	               Bangldash
2	          Chines Yan	5	China

Code
private String strConnection = "Data Source=.\\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|Database1.mdf;User Instance=true";
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindCurrencydropdown();
            }
        }
        protected void BindCurrencydropdown()
        {
            //conenction path for database
            SqlConnection con = new SqlConnection(strConnection);
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from Table1", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            con.Close();
            DropDownList1.DataSource = ds;
            DropDownList1.DataTextField = "CurrencyName";
            DropDownList1.DataValueField = "ID";
            DropDownList1.DataValueField = "CurrencyCode";
            DropDownList1.DataValueField = "CountryName";
            DropDownList1.DataBind();
            DropDownList1.Items.Insert(0, new ListItem("--Select--", "0"));
            DropDownList1.SelectedIndex = 0;


        }

        protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
       If            DropDownList1.seleceteditem.ToString()
     {
                      TextBox1.Text =””;
                        TextBox2.Text

        }

    }
}

please help me to solve it