Write top quality, interesting articles that can be found nowhere else on the web.
The more you write the more you can earn and the better writer you will become.
You cannot make money by just sitting there and watching the screen, as with any job hard work is the key. However writing on sites like this can be more fun and more rewarding and in time less work than a 9 to 5 can be.
So choose a topic you know a lot about and check the web for what is out there. Then set about writing the article, making it different to what is already there. Use the guide in the top right of the editing screen to help you write an engaging article and read all the material available on writing great hubs.
Don't be afraid of a little hard work at the beginning as the fruits of your labor will become apparent in time.