First find the downloadable template:
Go to System->Configuration->Advanced->Developer , select the type of store in the drop-down list in the upper left corner, expand the Debug section and set all 3 parameters to Yes
Download the content in question in the interface. There will be a red frame around the area with the text you want to translate, and you should also see the path to the downloadable template.
Then edit the template file. Try the following:
echo $this->__("I Need To Translate This Text");
The __() method is a text translator method that belongs to Helper_Abstract, from which all helpers are distributed.
This will make translations based on the CSV file in:
/path/to/magento/app/locale/
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