First, insert the provided software disc into your optical drive to start the DiskStation setup wizard offering a menu with interesting options.
You better read the Quick Installation Guide first. It will help you with the physical installation of the NAS, the HDDs etc.
After you finish reading the Quick Installation Guide, install the Synology Assistant. It will guide you through the installation of the operating system on the disk(s) you put into the NAS. The Synology Assistant, once installed, will find the NAS on your network, identify its model number and its serial number and will, if an operating system hasn't been installed yet, guide you through the installation process. If you have access to the internet, download the latest version of DiskStation Manager (DSM) from Synology's FTP instead of procuring and using a hard copy of DSM on a disc. Downloading the operating system will make sure your install is up-to-date. You can directly connect to the NAS through the Synology Assistant to set up your DS713+'s parameters— it also gives you the ability to check on your NAS's resources, upload some photos, or check the printers attached to it.
The above screenshots show you the steps you have to take to install the DSM operating system on the DS713+. The whole process is fully automated, very easy to follow, and doesn't take too long. You will be redirected to the login screen after the installation process is complete.
Software
The bundled software disc also includes a program, the Data Replicator, to make backups. The latter allows you to backup and restore files easily and quickly.
The Synology Cloud Station software allows you to sync files up between your NAS and your workstation or client PCs. You can download the software at Synology's download center