Hi Indradeo, 

Kindly refer below sample.

HTML

Default

<table>
    <tr>
        <th>Id:</th>
        <td><asp:TextBox runat="server" ID="txtId" /></td>
    </tr>
    <tr>
        <th>Name:</th>
        <td><asp:TextBox runat="server" ID="txtName" /></td>
    </tr>
    <tr>
        <th>Country:</th>
        <td><asp:DropDownList runat="server" ID="ddlCountries">
                <asp:ListItem Text="Select" Value="0" />
                <asp:ListItem Text="United States" Value="1" />
                <asp:ListItem Text="India" Value="2" />
                <asp:ListItem Text="France" Value="3" />
                <asp:ListItem Text="Russia" Value="4" />
            </asp:DropDownList></td>
    </tr>
    <tr>
        <td><asp:Button Text="Login" runat="server" OnClick="btnLogin_Click" /></td>
    </tr>
    <tr>
        <td><asp:Label runat="server" ID="lblMessage" /></td>
    </tr>
</table>

Index

<table>
    <tr>
        <th>CustomersId:</th>
        <td><asp:Label ID="lblId" runat="server" /></td>
    </tr>
    <tr>
        <th>Name:</th>
        <td><asp:Label ID="lblName" runat="server" /></td>
    </tr>
</table>

NameSpaces

C#

using System.Data.SqlClient;
using System.Configuration;

VB.Net

Imports System.Configuration
Imports System.Data.SqlClient

Code

C#

Default

protected void Page_Load(object sender, EventArgs e)
{

}
protected void btnLogin_Click(object sender, EventArgs e)
{
    int countryId = 0;
    string conString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    SqlConnection con = new SqlConnection(conString);
    SqlCommand cmd = new SqlCommand("select * from CustomerTest where CustomerID=@Id and Name=@Name and CountryID=@Country", con);
    cmd.Parameters.AddWithValue("@Id", txtId.Text);
    cmd.Parameters.AddWithValue("@Name", txtName.Text);
    cmd.Parameters.AddWithValue("@Country", ddlCountries.SelectedValue);
    con.Open();
    SqlDataReader reader = cmd.ExecuteReader();
    if (reader.Read())
    {
        Session["Id"] = Convert.ToInt32(reader["CustomerID"].ToString());
        Session["Name"] = reader["Name"].ToString();
        countryId = int.Parse(reader["CountryID"].ToString());
    }
    else
    {
        lblMessage.Font.Size = FontUnit.Large;
        lblMessage.Text = "Invalid credentials";
        lblMessage.ForeColor = System.Drawing.Color.Red;
    }
    reader.Close();
    cmd.Dispose();
    con.Close();

    switch (countryId)
    {
        case 1:
            Response.Redirect("Index.aspx");
            break;
        case 2:
            Response.Redirect("Index1.aspx");
            break;
        case 3:
            Response.Redirect("Index2.aspx");
            break;
    }
}

Index

protected void Page_Load(object sender, EventArgs e)
{
    if(!this.IsPostBack)
    {
        lblId.Text = Session["Id"].ToString();
        lblName.Text = Session["Name"].ToString();
    }
}

VB.Net

Default

Protected Sub btnLogin_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim countryId As Integer = 0
    Dim conString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Dim con As SqlConnection = New SqlConnection(conString)
    Dim cmd As SqlCommand = New SqlCommand("select * from CustomerTest where CustomerID=@Id and Name=@Name and CountryID=@Country", con)
    cmd.Parameters.AddWithValue("@Id", txtId.Text)
    cmd.Parameters.AddWithValue("@Name", txtName.Text)
    cmd.Parameters.AddWithValue("@Country", ddlCountries.SelectedValue)
    con.Open()
    Dim reader As SqlDataReader = cmd.ExecuteReader()

    If reader.Read() Then
        Session("Id") = Convert.ToInt32(reader("CustomerID").ToString())
        Session("Name") = reader("Name").ToString()
        countryId = Integer.Parse(reader("CountryID").ToString())
    Else
        lblMessage.Font.Size = FontUnit.Large
        lblMessage.Text = "Invalid credentials"
        lblMessage.ForeColor = System.Drawing.Color.Red
    End If

    reader.Close()
    cmd.Dispose()
    con.Close()

    Select Case countryId
        Case 1
            Response.Redirect("IndexVB.aspx")
        Case 2
            Response.Redirect("Index1VB.aspx")
        Case 3
            Response.Redirect("Index2VB.aspx")
    End Select
End Sub

Index

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        lblId.Text = Session("Id").ToString()
        lblName.Text = Session("Name").ToString()
    End If
End Sub

Screenshot