Importing products
On your store's dashboard there's an Add your products link.
At a minimum a product needs a name and a price. You can also add an SKU if you have SKU Management enabled.
Product variants can be added to the product from this screen. Each variant has to have a name. A variant can also override the product's price and it can have an SKU. Read more about variants and SKUs under product variants.
Now for the best part: Upload images of your product by selecting them or by dragging and dropping images into the labelled area. The first image will become the product's thumbnail and the rest will be added with it to the product's image slideshow.