The joys of homeassistant! So many ways to do things!
If you want to use the stream component you simply add
stream:
To your configuration.yaml file.
Now you also need to have a camera defined to stream from.
There are several ways to do this depending on the camera and its capabilities.
You can start with the generic camera config.
Go all the way down to the bottom of the page for the live stream.
Hope this helps a bit.