Plugin Name

After you clicked on the 'Activator Settings' link in the 'Settings' menu, you will be able to generate a shortcode for your script. This shortcode must be placed in a post, page or anywhere you want to use it.

Simple :

1. In the plugins folder(http://yoursite.com/wordpress/wp-content/plugins/activator/) place a new script with the following content: jQuery(document).ready(function($) { alert('Hello World!'); });
2. In admin page, look in "Settings" for "Activator Settings": -fill out the required fields and push the button : "Generate shortcode" -copy and paste the shortcode in a post, page etc.
3. Save it navigate to a page from your site. The alert itt will show up only on the specified page, post or else.

Be patient, I do this in my spare time.