This is a cookiecutter (project template) for getting started on building with Ergo on Scala. Just clone this project and start coding your smart contract.
You can use the simulator as unitests to mock states of the blockchain. Check the sample unitest.
Make sure you install SBT and the JVM, for which you can find plenty of tutorials online. You can then import this project into your favourite IDE to start coding.
once you have installed sbt you can do:
sbt test