1. Go to Content>>Article Manager
2. Select the article you want to edit
3. Select where in the article you would like to add / change / delete content.
* The default article editor acts very similar to Word in functionality, so to use HTML/CSS editor you select the "Show/Hide" link
Once selected the JCE editor dissapears and you are able to use HTML to add content.
4. Save your changes
Note: If you do not see your changes please clear your browers cache and Joomla's cache.