Write

When you click the link to write a mail, that's just what you're doing. You type the player's name in the address box and go from there.

You can put a subject in the subject line or leave it blank, it doesn't really matter. Some players like to know if it's a question you're asking or just there to chit-chat.

Now you can type your message in the big box beneath the subject line.

Those little button boxes above your main message box allow the box to be resized; the + makes it taller, the - smaller, and the arrows increase or decrease the width.

After you finish writing the message, you're once again presented with several options. Each of the buttons below your main message box has a similar, yet specific, function. You can just send the message, which will take you back your inbox; if you choose the send and close button, your message will send and your mailbox window will close automatically; and if you choose to send and return to the inbox, it does just that: after sending your message, you'll be redirected to your main inbox (this is helpful for multiple conversations).