First you must dispatch the report (if you havent already updated it using other means), then you must get the results endpoint to get the results.
When you dispatch the search, you will get a SID (search id). You use that SID in your quest for the results over here at the search/jobs/$SID$/results endpoint:
Remember that alerts, reports, and searches are all just searches. So the best examples I know of are here in the rest tutorial for searches: