The simulators work exactly like the hardware.
One way to get there is to enter the name of the waypoint on the active flight plan page. It will ask you if you want to create that waypoint. That takes you to the page that permits you to back into the LAT/LON box and modify it to your choice. And, further up on that page you can even create a waypoint using radial/distance or radial/radial.
It's all covered in the manual.
