There are many ways how to earn money online. For exmaple you can create a blog of your own and monetize it for advertisements. You have several options to monetize, for example, Google Adsense, Infolinks,
this website also provides cool service. These companies pay you for the ad and clicks for the advertisements that you display on your blog or website.
All you gotta do is choose a topic and start writing on it you can write blog on any topic like
Fashion
Sport
Music
Fun
Entertainment
Movies
Love
Romance
Business
Games
Poems etc.
These are the just example you can start with any topic you like.