CKEditor is a WYSIWYG HTML editor, available as a Javascript library. This could be used as part of a simple CMS.
Installation and testing
Download the JavaScript library
It resides in its own directory, so deploy it on your website where it can be accessed by your webpages.
Import library using script tag
<script type="text/javascript" src="/ckeditor/ckeditor.js">
The example above assumes you have uploaded it into /ckeditor/
on your server.
Draw a textarea and replace with a CKEditor instance
<textarea id="editor1" name="editor1">Sample initial text</textarea>
<script type="text/javascript">
CKEDITOR.replace( 'editor1' );
</script>
Instead of a textarea that can only edit pure text, you can use CKEditor and replace the textarea with an editor. The data from the editor is retrieved as HTML text, so you can still save it and use it later without the CKEditor library.
Add a button to get the value for testing purposes
<button id="editTest">Test</button>
<script type="text/javascript">
$('#editTest').click(function () {
alert(CKEDITOR.instances.editor1.getData());
});
</script>
When the button is clicked, an alert with the editor data will appear.
Screenshots
CKEditor in HTML mode
CKEditor in HTML mode
CKEditor in source mode
CKEditor in source mode