Assuming you already installed DotNetNuke, the associated italian language package and the module, you need to log in as host, go to languages item in host menu, select the language editor. Activate option "system"(!), select your language and check "highlight pending items". then select localResources :: DesktopModule :: <moduleName> in the tree on the left and you get displayed all entries per file. Edit the values for each key and save the file, repeat until all module's files are done. Check the result by viewing the module, if you are satisfied, you can create a distributable language pack file from host :: languages menu item.

There's another way to translate (quicker - i prefer this solution) a module. 
First you copy the resources file (normally in the directory App_LocalResources) and rename the filename for your localization code. Here's an example: the original file is namexy.ascx.resx  - i'm from austria,  so the austrian/german file would be called namexy.ascx.de-AT.resx .
Then you open the file you want to translate ( namexy.ascx.de-AT.resx). It's a XML file (what editor you prefer) and translate all the content in the <value> ... </value> Tags. Here's an example:

From:
...
<data name="lblContent.Text" xml:space="preserve">
    <value>Content</value>
</data>
...
To:
...
<data name="lblContent.Text" xml:space="preserve">
    <value>Inhalt</value>
</data>
...

That's it!

Don't forget that you must activate your language for your portal (admin->languages).

good luck!