Server GUI 3 is a simple user interface that allows you to create configurations for dedicated Serious Sam 3 servers. The configuration files can be transferred to another server and can be imported back into Server GUI if required.
To install Server GUI 3, simply extract the package you downloaded to a folder and run it. You will also need .Net Framework 4.0 for it to work. Install this from here: http://www.microsoft.com/download/en/details.aspx?id=17851
Simply set all the options you want and click "Save". This will give you a window where you can select a location for your configuration file. If the file is saved, you can click on "Launch", which will show you another window where you can load any configuration file and load it into the dedicated server.
To load a configuration file, click the "Load" button and find the configuration file. If it's recognised by Server GUI 3, it will load and you can edit it.
To make scripts, just check the scripts folder. It's not too difficult to figure out how it works.