If you are interested in earning Bitcoin online here it is some of the below options
Paid-to-Click Websites
Bitcoin Faucets
Micro Jobs on Coinworker
Writing about Bitcoin
BitcoinTalk Signature Campaigns
Bitcointalk Bounties
Writing for blog and news Find jobs on  Coinality
Provide Bitcoin-related services
Bitcoin Lending  on BitBond or Bitcointalk
Bitcoin Mining
Bitcoin Trading
Day Trading
Trading Bots
Bitcoin Futures
Binary Options

Here it is a detailed guide about all the ways listed above:
How to Make Money with Bitcoin