select the info that you want into a datatable,
set the datatable as the datasource for the dropdown. call the databind function. and make sure you specify in the dropdown control which columns have correspond with the DataValueField and DataTextField

can u give code for the get data from database in dropdown list

please give me the source code to retieve data from database todropdownlist in c#.net

You can add data that is returned from a reader the same way you would programmatically add items to a combobox (combobox1.Items.Add(*Object to add to combobox*);

Here is a sample of code that I did a while ago, this reads all of the Columns on a particular table and adds it to a combobox.

eg: Label=DropDownlist


protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
loadFrom();
}

}
public void loadFrom()
{
string insertstring = @"select * from ddlFFromDB";
SqlConnection conn = new SqlConnection("Server=SSK- PC\\MSSQL2008;database=*******;User ID=******;Password=*********;");
conn.Open();
SqlCommand cmd = new SqlCommand(insertstring, conn);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataSet data = new DataSet();
adapter.Fill(data);
conn.Close();


ddlFrom.DataSource=data.Tables[0];
ddlFrom.DataValueField = "FromId";
ddlFrom.DataTextField = "From";
ddlFrom.DataBind();

}