It is pretty straightforward. Connect the network/CAT-6 cable to your router, plug in the power cable, turn it on and wait about 5 minutes. Start9 should provide the ***.local address for you to connect to using a browser from any other computer on the same local network.

If not, you can use a tool called Angry IP Scanner to see all network devices on your local network by IP address. You can copy/paste each IP into a browser and it should bring up the StartOS login page.

The first time you come to the log in page, you'll need to download and trust your server’s Root Certificate Authority (Root CA) to establish a secure (HTTPS) connection with your server. You only need to do this once (per computer you intend to log into your Start9 server from).

Log into Start9 and under System > About, it will give you the ***.local name for that computer. To install apps, go to Marketplace, under "Start 9 Registry" change to the community registry and install Bitcoin Knots. Run Knots and it will take a couple days to grab the IBD (initial blockchain download, aka: all the Bitcoin blockchain transaction/block data). You'll also want to install electrs and Mempool, at a minimum.

I hope that helps. Let us know if you have more questions.