Try these,
private void btnSubmit_Click(object sender, System.EventArgs e)
{
Response.Redirect("Webform2.aspx?Name=" +
this.txtName.Text + "&LastName=" +
this.txtLastName.Text);
}
And in "Webform2.aspx" page.In it's load event,
private void Page_Load(object sender, System.EventArgs e)
{
this.txtBox1.Text = Request.QueryString["Name"];
this.txtBox2.Text = Request.QueryString["LastName"];
}