How Do I Write A Webmethod So That My Login Page Accesses The Database To Log The Persons Details My Code For My Login Is As Follows,Need A Webmethod

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.OleDb;
using System.Web.Services;
using System.Data;
using System.Xml.Linq;

public partial class Login : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if(Request.Cookies["LoggedIn"]!= null && Request.Cookies["LoggedIn"].Value == "true")
        {
            Response.Redirect("Home.aspx");
        }
    }
    protected void BtnForgotPassword_Click(object sender, EventArgs e)
    {
        Response.Redirect("ForgottenPassword.aspx");
    }
    protected void BtnRegister_Click(object sender, EventArgs e)
    {
        Response.Redirect("Register.aspx");
    }
    protected void BtnLogin_Click(object sender, EventArgs e)
    {
        UseDatabase usedb = new UseDatabase(Request.PhysicalApplicationPath + "App_Data\\ProjectDatabase.accdb");
        string queryString = "SELECT * FROM [RegisteredDetails] WHERE EmailAddress = '";queryString += txtLoginEmail.Text
            + "' AND Password ='"; queryString += txtPasswordLogin.Text + "';";
        usedb.connectToDatabase();
        OleDbDataReader dbReader = usedb.ExecuteQuery(queryString);

        if (dbReader != null && dbReader.HasRows)
        {
            HttpCookie loggedInCookie = new HttpCookie("Logged In", "true");
            Response.Cookies.Add(loggedInCookie);
            Response.Redirect("Home.aspx");
        }
        else
        {
            lblError.Text = "Please enter correct Login Information" + " "+"Incorrect Username or Password";
        }
        usedb.disconnectDatabase();
    }
}