You’ve probably used a WYSIWYG editor, but you might not even be aware that you have. If you’ve ever used some sort of editor where you can highlight words, change their formatting, and have those changes be instantly visible to you, then you’ve used a WYSIWYG editor. For example, Microsoft Word is a WYSIWYG editor!
WYSIWYG editing is different from directly editing using a markup language, such as HTML or XHTML. When you use a markup language, you must type in tags that assign styles instead of just clicking a button. Joomla and web-based email, such as Yahoo! and Gmail, use simple WYSIWYG editors that let you format content by highlighting text and clicking a button.
Many other Joomla editors are also available.
I prefer JCK Editor.
Visit http://www.joomlackeditor.com and register.
Download the latest editor.
To install or upgrade go to the back-end Administrator section and login with your 'Username' and 'Password'.
Once logged go to ‘Extensions’ and click on ‘Install/Uninstall’ (‘Extension Manager’ in Joomla 1.6). This will take you to a page titled ‘Extension Manager’.
Under `Upload Package File’ click on `Browse…’-> Navigate to the JoomlaCK Zip file -> select it -> click `Upload File & Install’.
The system will now automatically install or upgrade the Plug-in or Component for you. Once completed it will inform you that the application has been successfully installed.
Finishing, you need to set your sitewide global editor. You do this in the backend in the Global Configuration dialog box, which you open by selecting Site->Global Configuration. You see a drop-down box for your default WYSIWYG editor.