To

Here you enter the email address of the recipient or click the icon to select them from your address book

You can shows the Cc and Bcc boxes by clicking

Cc can be used to send a copy to other recipients where all recipients can see who it has been sent too whereas Bcc hides additional recipients (which is what you should use if sending to multiple recipients)

Subject

Here you enter the subject (title) of your email message, it is advisable not to leave this blank as many email systems will treat it as junk mail (spam)

Toolbar

Use this toolbar to format your message i.e. change font style (e.g. bold, underline), font colour, alignment, insert lists etc

You can also click the icon to attach a document/photo to send with your email

Message

Here you type the main body of your email message

Send

When you have finished composing your message click Send