First turn on the Locale module. Then, if your text is hardcoded, wrap it in the t() PHP function as follows
Another important thing Francesco - make sure you write the strings with the t() around them in English and then translate them as described by JP into Italian. It doesn't work the other way around - source strings have to be in English.
Not sure if you still will need to have different template files once you know how to do this. But if you are in need of further customisation, it's probably better to just stick with one template file but use the functions available to check the current page language and then do an if/then statement. I think page.tpl.php is automatically given a variable called $language which tells you the current language being used.
Regards John Salt Websites internationalised web development http://www.saltwebsites.com/