How do I get legs like Miranda Kerr?!

I used to use the rowing machine and it's left me with big, blocky muscles. I now use a stationary bike three or four times per week (low tension and speed for at least three hours per session) and whilst it has slimmed my legs, it hasn't toned them. My thighs are eighteen inches but the muscle at the front of them sticks out and makes them look bigger than they actually are. What exercises or machines can I use to minimise this muscle. I really want thighs like Miranda Kerr:
http://sportige.com/wp-content/uploads/2…