我如何使用C＃在ASP.NET中发送html邮件？

I have a ASP.NET Application that add data to a DataBase and get data from this database. This Application is for creating a guestconnection to our network. If a User is add to the database and the Radius Server give the ok the User get e email with his login data. username and password. I want to make a html mail. But I don't know how I can do this in ASP.NET and so I read a few tutorials about that and I found this Code: I have a ASP.NET Application that add data to a