http://sparrowa7io5pz6ud3ehqzosvepbxbxt2zphmkjsylp2zgxooko23pqd.onion/docs/best-practices.html
The Quick Start guide explains how to connect Sparrow to an Electrum server - just replace the server URL with your own.
You can also connect via Tor if your server provides a .onion address, which means you can connect privately from anywhere.