Download the latest disk image for Hass.io from the Home Assistant page. We will be using the Raspberry Pi 3B+ for this project so that is the one you want to get, but if you want to use another Pi version, pick that one from the downloads page.
If needed, use the SD Card Formatter to format the MicroSD Card and remove any partitions.
Use Etcher to install the boot disk image onto your MicroSD card.
Once finished, eject the MicroSD card and put it into the MicroSD slot for the Raspberry Pi.
Use the Ethernet cable to connect your Raspberry Pi into an available network port on the back of your WiFi Router.
Plug the Raspberry into power using the Micro USB connector.
It can take up to 20 min for Hassio to install. After that time you should be able to access the user interface by going to http://hassio.local:8123 from and web browser on your local network WiFi or Ethernet connection.