One way to get started is to watch Chris's talk on Scala 3.
Afterwards you probably want to take a look at the README for the scalac-scoverage-plugin and your build plugin of choice.
If it is sbt you can also take a look at the sbt-examples
and the scripted tests in the sbt-scoverage repo.
If you have questions, please feel free to reachout on Gitter.