请告诉我在哪里需要提及以下代码。我很困惑和学习,所以你能帮我一步一步吗?
// set credentials
Sendgrid mail = new Sendgrid("<sendgrid_username>","<sendgrid_password>");
// set email data
mail.setTo("foo@bar.com").setFrom("me@bar.com").setSubject("Subject goes here").setText("Hello World!").setHtml("<strong>Hello World!</strong>");
// send your message mail.send();