hi! right now we don't have specific examples that uses just jsreport-core.
however here are some steps that you need to do:
the best will be to add jsreport-fs-store or jsreport-mongodb-store and configure your instance to use it, then you can add jsreport-reports extensions that is designed to store the reports on the configured blobStorage of your instance, you can configure the blobStorage to be based on the file system (fs-store) or in mongodb (mongodb-store), you just need to specify it in your config. then when you are rendering make sure to pass the options needed to save the generated report.