Find the section ‘Free 2017 Discovery Pass’ and click Order Now
Click Add to Cart
Click Proceed to Checkout.
Click Continue Checkout
Enter your billing and shipping address, and click Next
Click Order and you will receive an order confirmation.
After this it might take upto 6 weeks for you to receive the free pass. If you are planning to visit a park before this 6 weeks, then I believe you can get a pass directly at the park office at the entrance of the park you are visiting. Happy exploring!