Improving Ankle Dorsiflexion
The routine in this article is great for improving your ankle range of motion, particularly dorsiflexion.
The squat is a great position to help with improving your dorsiflexion as well. This tutorial shows some preparation movements and tips on the squat itself to help you improve your ankle range of motion.
Try these out, preferably every day if you can, for a few weeks and you should start to see improvements!