Would also like to know if we are participating automatically or if we have to to something

According to the this, you don't have to do anything as long you have ETH and BTC in your wallet.
The Proposed Airdrop:
- Total tokens 1,000,000,000 XNN - 70% airdropped:
- 300,000,000 XNN proportionally airdropped to all ether addresses with >0.1 ether
- 200,000,000 XNN airdropped based on bitcoin proof-of-holding
- 200,000,000 XNN airdropped via proof-of-individuality mechanisms
- Much of the remaining XNN will be used in social media/bounty/referral campaigns and developer incentives