As Mr Boat said, its pretty simple but has to be done through Training Centre. You can upload from garmin Connet as well, but you can only do one workout at a time (i.e. the new one overwrites the old one).
Also one "gotcha" I experienced was that it wouldn't upload the schedule from the training seciton of the RW website. I had to delete the default ones that were pre-installed to make sufficient space for them, and then it worked.