You can use the self-hosted Jitsi server through Riot, through an Integration Manager like [Dimension](docs/configuring-playbook-dimension.md) or directly at `https://jitsi.DOMAIN`.
To use it via riot-web (the one configured by the playbook at `https://riot.DOMAIN`), just start a voice or a video call in a room containing more than 2 members and that would create a Jitsi widget which utilizes your self-hosted Jitsi server.