Thanks in advance :)
When you start the description process, the MOO takes your lines of input one after another and does not echo anything back to you until you're done. It won't look like anything's happening when all you're doing is writing lines of description. When you're finished, enter a single line with nothing but a dot . (period) on it and hit Enter again, this will make the MOO stop taking any more input to your description and return you to regular command-entry mode.
There are other places in the game where the same convention is used, where the MOO expects multiple lines of entry (a line is typing words until you hit the "enter" key, a "line" does not mean typing till you reach the side of the screen and see your words wrap) and then expects a single dot on a line to signal the end of your text input, so, it's good to get used to this early in your career. Entering @history is probably the next place where you're likely to encounter this.
