Use a mapping site to plot a ride, (Bike Hike is my mapper of choice). Save as a gpx or tcx file on to your computer. With the 200 connected to your computer. Drag and drop the file into the 200's new file folder and it will convert to a route to follow.
To follow the route. Find route, select route/course, press start and away you go and it will record your journey.
It does take a little while to get used to the breadcrumb trail you follow. You have to be especially aware of junctions and roundabouts. But as Phil said also, it will tell you if your are off route.