If you'd like to change some of your command line login defaults, but don't know where to find the file, it's located here:
/Users/[name]/.tcshrc
[name] should be replaced with your username, of course. If you don't have this file, you can create it from the command line or a GUI editor.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010330121007676