The install routine will show you the changes it will make to the web.config in order to set the database connection up. It will also change the resource provider (via the globalization tag) so the software will use the database for language resources rather than the file which is used by the install routine.

If Kartris cannot write/modify the web.config file, it will give provide a link for you to download the new edited file. You will then need to load this to your site, via FTP or just copying and pasting (on a local site). You may need to restart the site if the file is locked. Generally the site will restart after the web.config is updated.