I made a Django admin site using Django development version but it isn't being styled:
Django does not serve static files on it's own. You have to tell it where the files are.
The ADMIN_MEDIA_PREFIX in the settings.py will point Django in the right location.
Since you're using the development version, you'll want the dev-specific document for static files how-to. Adam's link will lead you to the 1.2 version.