The way to send a message to someone by email is to first open the sender's email client, such as Yahoo!, AOL, Gmail, or Hotmail. From there, click in to the box to type in the email address of the person the message is going to. From there, type a subject in the Subject line. Then click below to begin the message. Once finished with the message, click Send, which is usually at the top of the page. The person will receive their email within a couple of minutes, depending on the email client.