MOTD stands for Message of the Day, and has long been something that administrators use to convey important information, such as scheduled shutdowns or maintenance to users. The MOTD should be provided for users after they log in but before they come to the shell prompt.
The file the message of the day is kept in is /etc/motd. The contents of this file are displayed every time a user logs in. It's that simple. When you first install the system, the file is empty.
Start your favorite editor to edit /etc/motd. In this case, I use vi, so the command vi /etc/motd will do the trick.
Press the I key on your keyboard to begin inserting text.
Type your message.
Press the Esc key to stop inserting ...