To localize various messages and screens of I4, as the first thing, verify if in the i4 Web.Config exists the line:

<system.web>
   <globalization enableClientBasedCulture="true" uiCulture="auto"/>

If it is not there, add it.

Then, assuming you're translating into Italian language, under ..\Web\i4\App_GlobalResources, copy the file adminres.resx into adminres_it.resx, and then translate it.

Moreover, still assuming you're translating into Italian language, under ..\Web\i4\App_GlobalResources, copy the file i4.resx into i4_it.resx, and then translate it.

Moreover, locate the folder ..\Web\i4\js\lang with the file messages.txt, and then, still assuming you're translating into Italian language, copy the file messages.txt into messages_it.txt, and then translate it.