How to send HTML Email from ASP.NET using your Gmail account?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Mail;
using System.Net;

public class Gmail
{
    /// <summary>
    /// Sends the mail.
    /// </summary>
    public string SendMail(string toEmail, string subject, string body)
    {
        string returnMsg = string.Empty;
        SmtpClient client = new SmtpClient(); 
        client.DeliveryMethod = SmtpDeliveryMethod.Network; 
        client.EnableSsl = true; 
        client.Host = "smtp.gmail.com"; 
        client.Port = 587;                
        // setup Smtp authentication               
        NetworkCredential credentials = 
            new NetworkCredential("your_account@gmail.com",
                "yourpassword");               
        client.UseDefaultCredentials = false;                
        client.Credentials = credentials;                                 
        MailMessage msg = new MailMessage();              
        msg.From = new MailAddress("your_account@gmail.com");
        msg.To.Add(new MailAddress(toEmail));     
        msg.Subject = subject;          
        msg.IsBodyHtml = true;
        msg.Body = string.Format(body);  
        try { 
            client.Send(msg);
            returnMsg = "Message has been successfully sent."; 
        }
        catch (Exception ex) 
        { 
            
            returnMsg = "Error occured while sending message." 
                    + ex.Message; 
        }
        return returnMsg;

    }
}