You need to download the installer here and run it as administrator.

The installation process requires restarting the computer connected to Internet.

The installation process creates the "dekaedra" folder within the "Documents" folder or "My Documents" folder of administrator user who did the installation.

If you have an antivirus system, it can warn of danger, in which case you must warn that it is not.

Once installation is completed you need to configure dekaedra, for it you must read this.