how to claim free book give away coupon

hi,
in some activity I won and received an email attached with pdf "OReilly Free Book Give Away Coupon". Its from authentic source. But I don't know how to claim it. Tried to ask with sender, but couldn't listen back.

Content of this says and seems very generic no where mentioned book name:

"Congratulation! You get a free ebook. Visit Oreilly to register it."

But I am not seeing any code or book name. How to get it, kindly suggest.

Attaching the coupon also.