I suggest in your next question in Stackoverflow you demonstrate the code, or API call that you achieved so far to better illustrate your problem.
Now, the HERE Routing API requires a lat/long as input. So you would have a lat/long for your origin and a lat/long for your destination.
For example:
https://route.api.here.com/routing/7.2/calculateroute.json?app_id={{app_id}}&app_code={{app_code}}&waypoint0=-27.406755,153.162592&waypoint1=-35.298098,148.13882&mode=fastest;car;traffic:enabled&departure=2019-04-03T06:00:00Z&representation=navigation
waypoint0 is where you start, and waypoint1 is where you finish. Obviously you could have more waypoints if you wanted to.
If the only thing you have is the address in string format, you must then use HERE Geocoder API to translate that string into a lat/long.