Your rights to send or delete messages are set by your administrator or instructor. Generally, students are granted posting rights. If you've been given the required rights, you can post messages directly to the list, either as new messages or as replies to existing messages. When you reply to a message, your message is threaded to the one you've replied to. Subsequent replies become part of the same thread.
Any new message posted to a discussion list can start a new thread.
As soon as someone posts a new message to a discussion list, the Discussion Lists icon on your Home page displays a flashing New icon. Any new messages on a discussion list are identified by a red N . Any unread messages are identified by a blue U .