I agree that Magento is the way to go when getting started. There's also OpenCart, not as widely used but can provide a different perspective on how e-commerce can be built. I would stay away from Woo Commerce, I try to avoid anything Wordpress just because I don't trust it. I've worked on from-scratch .NET e-commerce sites, Magento, OpenCart, and Demadware.
You probably don't want to get into Demandware just yet, but if you do, the need for skilled Demandware developers exceeds the supply currently.