Install Synology assistant on PC and run it.
It will detect new Diskstation as unconfigured and not installed.
Install the .pat file, wait until reboot and use browser from PC to connect to DSM for managing it.
Remove monitor and keyboard from NAS and leave the USB flash drive inserted for next reboots.
ah yup got it, thanks now to work out how to RAID 5 edit: looks like its that by default