copy the 'real-wysiwyg' directory to your 'wp-contents/plugins' directory.
Activate the Real WYSIWYG plugin in your plugins administration page.
If your theme supports Real WYSIWYG then the editor window should now look
the same as your posts. Otherwise, you may need to configure Real WYSIWYG via the options
menu to include any extra stylesheets your theme may have and to include any extra css
so that the editor body will be correctly styled.
For instance, for the default them, the following CSS is some of what is added to the Extra CSS field:
background:transparent url('../../themes/default/images/kubrickbg-ltr.jpg') repeat-y scroll center top;
Requires: 2.2 or higher Compatible up to: 2.2 Last Updated: 2007-9-20 Downloads: 27,713