Byteball announces that they will airdrop byteball coins for everyone who has a Steemit, account. Rewards will vary as follows. From their official Medium post.

Rewards for Steem users
When you prove your Steem username, you will also receive a reward based on your Steem reputation and for referring other users. The higher your reputation the bigger the reward.

The attestation rewards are as follows. Note that these rates are likely to change in the future, especially the starting reward at a reputation of 30 which is not too difficult to achieve:

Steem reputation above 30: you get a $10 reward
Steem reputation above 40: you get a $20 reward
Steem reputation above 50: you get a $40 reward
Steem reputation above 60: you get a $80 reward
Steem reputation above 70: you get a $160 reward
All rewards are paid in Bytes from the undistributed funds.

Your reward is split 50/50 between cash and a smart contract. This means that 50% of the reward is spendable immediately after attestation. The other 50% is paid to a smart contract that can be unlocked after one year. Once this time period is reached you will be able to withdraw the remaining 50% of the reward.

To claim your reward simply follow these steps.

1. Click here to download the Byteball wallet for your machine.

2. Once the wallet installation file is downloaded, simply follow the set up instructions until it's finished.

3. Once the wallet is downloaded, go to the Bot Store chat tab and click on "Steem attestation bot".

4. Follow the bot instruction to link your Steemit account to your Byteball address and voila, you'll instantly receive your Byteball coins.