It's a fairly straightforward concept that most people are familiar with by now -- if you have a bunch of stuff that you don't necessarily need but others want and are willing to pay extremely inflated prices for, you can auction off the items on eBay or other online auction sites. Simply gather your goods, create a seller's profile and start selling.
It sounds simple, but takes some practice to sell successfully. Creating persuasive and legitimate product pages for the goods you're selling will help get buyers interested. It's also important to set reasonable minimum bids to ensure that people will buy. And remember to deliver the kind of customer service that will garner positive feedback ratings and to communicate with buyers to let them know you're reliable. The more positive feedback you receive, the more people will be willing to do business with you. And that, of course, means more money.