You write articles (hubs) and publish them. All the better if they're high quality and you can spread links around on social media, develop an audience, etc.
After a while of this, you can qualify for a Google Adsense account if you don't already have one. You can also get affiliate accounts at Amazon.com and Ebay and put ads on your hubs.
It can take a while, but if you're good at it, and you develop a large audience, you can start earning money.
It took me about a year to get my first $50 payout, but now I'm making a nice little part time job earning every month. It really depends on how good you are, like everything else. I did a lot of research into what makes a good hub, how to draw an audience, etc. to make it happen.