Having just returned from 3 weeks of biking across the Netherlands and Germany, I wanted to share what I learned about using the fietersbond web site.
First, the Netherlands has two parallel bike networks, both of which can be used from this website. The "recreatieve" or green system is more scenic, but can be longer point to point. The "van-deur-tot-deur" or red system is more direct, but often uses bike paths that parallel the roads and highways.
When biking, direction signs often include both 'red' and 'green' routes to the same destination, with distances to let you know the tradeoffs.
I used the 'green' routing from Schiphol Airport to Haarlem, and it was a far more pleasant ride than the slightly more direct route most websites steer you towards.
To get the fietersbond.nl routings onto my Garmin, I used the free Garmin Base Camp application to import the tracks files created by the web site, and then had Base Camp convert the tracks into routes before loading them. It was fun jumping from Base Camp into Google Earth and then Google Street View to get a preview of parts of my route.
This was both my first European tour and my first time using a GPS... I definitely plan to return to Europe with my bike, and the GPS was a real asset.