Hi,
Did you check this article about the child themes?
http://www.gavick.com/documentation/wor ... ld-themes/If you are not using Child theme and do modifications, you'll have to update manually each file, during the theme update. (every update has changelog with list of the changed files).
Of course if you add only css modifications into css/override.css, there's no problem, you'll have to copy this file, update theme, then restore override.css file.
If you want to use child theme, activate in in your Dashboard -> themes section (if you didn't copy any files into your News2-Child directory, all files are loaded from News2 (parent).
Remember about the directory structure, e.g if you want to change content-archive.php file copy it into News2-Child directory, make your changes and now this file will be loaded from the News2-Child, rest files from News2. Copy only files which you want to change.