Download the above file, rename it from .txt to .php, and upload it to your plugins directory. Make sure you add this using the html/code editor in WordPress, not the visual editor. In new versions of WordPress, just click the ‘html’ button above the edit box. If you use the visual editor it will not work, as the actual code you entered will be seen on the page, instead of being processed by the script.
Example: How to use[DDET Click to expand!] Here is your text!
Click again to close!
EXPANDING TEXT PLUGIN FOR WORDPRESS