As someone who's been immersed in a number of online industries for quite some time, I know a thing or two about what it takes to succeed in this arena. However, just like you, I started at ground zero with little knowledge, but a great deal of passion. What I learned along the way were some invaluable lessons from failure that hurt at the time, but helped immensely in the grand scheme of things.
eBay is the most popular global auction site around and is a great place to sell items you no longer want. If you are looking to earn some extra cash, start out by looking around your house for things you no longer want; list them on eBay and watch as customers bid on them. You can also purchase clearance sale items and thrift store finds and make a couple dollars profit by listing them as well. The key to selling on eBay is to do your research and find out what the hot items are.