Clicking the New Reply option will allow you to add attachments, and set priorities (siticky, announcement) and calendar events, as authorities allow oer your settings. If you're making a simple reply, use the "Quick Post" option as it loads faster
and has less to sift through to post.
Clicking the "more options" link gives you the option to quote the previous message, attach your signature (or disable, depending on your settings) and the ability to receive email notification if a reply is posted to that thread.