Here are some basic terms that you will find in all email programs or email websites (such as YahooMail, GMail and Hotmail):
Attach/Attach File - Sends the file with the email (Just like attaching a document to a letter using a paperclip).
BCC - Blind Carbon Copy. A copy of the email will be sent to the names you put in this box. These names will be hidden from others receiving the email.
CC - Carbon Copy. A copy of the email will be sent to the names you put in this box. These names can be seen by others receiving the email.
Forward - Pass the email on to someone else.
New/Compose - Create a new email.
Reply - Only the person who sent you the email will receive your reply.
Reply to All - The sender and anyone who received a carbon copy of the original email, will receive your reply.