You will need to buy inventory, have your product made, or find a drop shipper. You are on your own with the first two, but I do have some tips for finding a drop shipper.

• If your product is information, then you can skip this step.

Finding A Dropshipper 

• You need to find a manufacturer or distributer that has inventory they can ship directly to your customers. In other words, don't buy your own inventory if you don't have to. You can act as a middle-man.
• There are advantages and disadvantages for using a dropshipper. Advantages include: (1) You do not need an initial investment in inventory, (2) You don't have to worry about shipping, and (3) You can offer more products. Disadvantages include: (1) Every middleman takes his or her share of the profits, which lowers yours return, and (2) A good drop shipper is difficult to find, but they are out there, it just depends on where you are looking.
• Because products are so different, this may be a challenging step. You can't just search "dropshipper" on the internet and find the pot of gold. With the boom of the internet came a boom of dropshipping scams. They want you to find the customers, and they get all the profit. Finding customers is harder than you think, and the profit margins these drop shippers offer are way too low.
• If most of your products are made by one manufacturer, the first step is to contact them directly. If they do not drop ship, ask them if they have any distributers. Follow the money trail and you should find what you are looking for. If the manufacturer is overseas, it will probably not work, but it is worth a try. Sometimes manufacturers will only work with business that have a business license, but if they will drop ship, then I would suggest you get it.