There are numerous ways to make money online. If you are the type who has always wanted to own your own store, but cannot afford the cost of starting a brick and mortar shop, an E-commerce website may be right for you. Even beginners who have never run a business before can handle these types of sites. Typically with this type of business you don't directly deal with products. That all gets handled for you by a distributor or parent company. All you have to do is set up the site, promote it, and then handle the profit from sales.
One option for E-commerce is to find distributors who will drop ship the type of goods you want to sell. After you find your distributor(s), you need to select how you want to set up your website. You can go with an all inclusive E-commerce hosting package (like Yahoo Merchant Solutions or similar system), which is nice because they give you tools for site design, catalogue building, and checkout tools. You can also design your own site, have it hosted through any web hosting solution, and incorporate checkout and catalogue tools yourself (checkout OScommerce.com for some cool open source solutions). Either way, you decide the items to list on your site. This method can be more time consuming to get up and running, but gives you more flexibility in the items you can carry.
Another form of E-commerce is where you partner with an existing company and they provide you with a "mirror" website. The downside to this type of system is that your inventory selection is typically limited to what is being carried by the parent company. If you are the busy type and are looking for something that is quick and easy to start up, this would be a good option. Everything is typically set up for you and automated, even the payment system installation. All that is left for you is to possibly tweak the site (in allowed) and promote it.
If you already have a website, a third option is affiliate advertising items for other companies. Many big name companies have affiliate programs you can join for free. You post links and banners to items and you get money for each item sold through your link. Companies like Amazon and Barnes & Noble only pay a small percentage for each sale, but have common and very popular consumer goods. Companies like Clickbank generally pay much more per sale, but tend to deal with informational products. The type goods you advertise should be determined by the nature of your website. If you already have steady traffic coming to your site and a target audience, this can be a good option for you.