Collection of links to articles that helped me set up my raspberry pi as a NAS: - https://pimylifeup.com/raspberry-pi-nas/

• Install NOOBs (or raspbian)
• Switch on device (default user pi password raspberry)
• Set up remote access ssh
• Change credentials

• Update system

  sudo apt-get update
  sudo apt-get upgrade

• Set up USB hard drives

  • Or check refer to my post

• Install and configure Samba