A description is what the player sees when the look command is executed. Your home room is the room you will enter every time you log on to GR and the room you go to when you enter the command home . It should be a room you own. Sometimes, it can be a room owned by someone else, e.g. a teacher. You must be in the room you want to make your home room.
Messages are what can be seen when certain commands.
Look at the messages which are already there before you change them to get an idea of how they work. Test them out by paging yourself, for example. It is most helpful to include your name in your messages, if you are going to change them. To get a list of everyone who's logged in, if they are idle, etc. There are two ways to talk to people who are in the same room as you.