Re: How, in the new Mozilla Firefox version do I go about finding how to add a "Subject LIne" or add an Attachment in sending or replying to e-mails?
Firefox doesn't do email, it's strictly a web browser.
If you are using Firefox to access your mail, you are using "web-mail". We might have an answer for you if we knew which web mail service provider this problem is with. Or, you could seek support from your service provider or a forum for that service.