im a little confuse of what is airdrop i cant understand how to take a bounty for it .. If you register or Sign up for the form can you earn a coin??
Airdrops and bounties are different things.
In an airdrop, you get an amount of coins for free just by providing your address. This can help promote a project.
In a bounty campaign however, you have to complete different tasks to get a "bounty". You could call it freelancing if you wanted to, but it's called bounty on BitcoinTalk. Tasks for bounty campaigns are usually translations, signature campaigns and social media campaigns. Some people also manage projects or write technical papers such as whitepapers.