A window will come up looking similar to the one displayed below. Hit your TAB key to advance or click your mouse to the next field. Hit TAB to advance further.
CC stands for carbon copy.
On their end, the message will note that it is a carbon copy. If you enter more than 1, separate them individually with commas. Just as above, enter full email addresses you wish to send a blind carbon copy to, separated by commas. Attachments can be any file on your local computer system you wish to send along with a message. An attachment can be anything from a JPEG image to a shareware ZIP file of a game.