<asp:dropdownlist id="ddlCountry" runat="server" >
<asp:listitem value="-1">Your Item</asp:listitem>
//add line items here
</asp:dropdownlist>
But you have to know which you are going to insert, Value or item.
and in db you have to specify the datatype for that column whether int (for value) and nvarchar (for item)
DropDownList1.SelectedItem; //it will insert the selected text
DropDownList2.SelectedValue
//it will insert value
Still if you need more clarification paste your code here.