i am doing login page

string SqlConnect = System.Configuration.ConfigurationManager.ConnectionStrings["Connect"].ConnectionString;
        SqlConnection Sqlconn = new SqlConnection(SqlConnect); 
        SqlCommand sqlcomm = new SqlCommand("select email,userpassword from signup where email='" + TextBox1.Text + "' and userpassword='" + TextBox2.Text + "'",Sqlconn);
        Sqlconn.Open();
        SqlDataReader dr = sqlcomm.ExecuteReader();
        if (dr.HasRows)
        {
            Session["email"] = TextBox1.Text;
            dr.Close();
            Sqlconn.Close();
Label1.Text = "Email-ID or Password you entered Is Valid !";
            
        }
        else
        {

            Label1.Text = "Email-ID or Password you entered do not match !";
            Label1.ForeColor = System.Drawing.Color.DarkGreen;

        }

protected void loginbtn_Click(object sender, EventArgs e)
        {
            string cmd = new "SELECT * FROM Users";
          
            SqlDataAdapter da = new SqlDataAdapter(cmd,con);
            DataTable dt = new DataTable();
            da.Fill(dt);

            string msg = "";         

            foreach(DataRow dr in dt.Rows)
            {
                if(unameTxt.Text == dr["username"].ToString() && pswdTxt.Text == dr["password"].ToString())
                  msg = "Success";
                else
                  msg = "Error";
                 
            }
        }