If you can write, it's pretty easy to make money online. There are hundreds of websites that are willing to pay for original written content. Some sites will share revenue with you, and some will pay you directly.
You can write poetry, fiction, or articles on just about anything. You can write about personal experiences, or write your own blog. There are many ways to make money writing online.
Content sites like Infobarrel, Hubpages, Squidoo, and Associated Content are websites that will share advertizing revenue with you, and are easy platforms to start with.
Blogging is a great way to make money writing as well. One of the best ways to start blogging is to use Blogger. It's easy to set up a blog, and you can put up Adsense as a way to make money. Blogging is ok, and it's easier to make your full Adsense amount instead of sharing with a content site, but you also have to do a lot more promotion to get a blog going.
My advice to make money writing online is to set up accounts at as many different content websites as you can. This way, you can reuse articles where it's allowed, so you don't have to write as much original work. Don't put all of your eggs in one basket. Websites go down all the time. I had over three hundred articles at Ehow, and was making three to four hundred dollers every month. When they decided to delete everyone's articles this year, I lost hundreds of dollars a month of passive income overnight, along with everyone else.
I like to see what the site's full potential is. I like to write at least a hundred articles at a site, and let them sit for at least six months or so before I determine if it is a money maker. I do this by writing up to five or six articles a day sometimes. At least as many as I have time for. I often write on similar topics, because running out of ideas is easy after you've written hundreds of articles. I take my best subjects from other sites, and write about those topics in more detail.
Once I've written my hundred articles, I go on to another promising content site, while letting the first one sit and mature. I usually don't even try to analyze a site for at least half a year or so.