Try this:
1st Page:
protected void login_Click(object sender, EventArgs e)
{
Response.Redirect("Default2.aspx?user_name='" + TextBox1.Text + "'");
}
2nd Page:
protected void Page_Load(object sender, EventArgs e)
{
if (Request.QueryString["user_name"] == null)
{
Label1.Text = "querystring not found";
}
else
{
Label1.Text = Request.QueryString["user_name"].ToString();
}
}
--Amit