All you have to do is (be in India, first of all), buy a Lumia 800 from Nokia's online shop or a store, sign in to your Nokia account (create one if you don't have one already) after which you should receive the offer via email or SMS and you should get your speakers in 7-20days depending on what area you are in.
That's a pretty cool offer, the play360 or PlayUp speakers have been on my wish-list for a while, lucky Indian consumers now have a chance to get one for free.
Here in the US, you still have to spend $150 or get the entertainment bundle with the Lumia 800, purity on ear headsets, luna Bluetooth and Play360 speakers for $899 🙁
Source:
Nokia India