You can create and publish a custom HTML module displaying your own code in Joomla 2.5 through the Joomla 2.5 administrative area.
Navigate to Extensions -> Module Manager. Click on the New icon and select Custom HTML as a module type. On the newly opened page enter the title of the module, select its position on the template and enter the Custom Output which should be visualized by this module.
You can assign this module to the pages where it should be displayed from the Menu Assignment sections on the same page. Make sure its status is Published, adjust the other settings and save the changes.
Reload your front page to see the result.
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