How can I start my own online store?

I want to have my own online store selling my own original fashion creations, but I have next to no idea on how to get started. I have no ideas on legalities or how much it would cost etc.. So far the best thing I've seen is this website called flyingcart.com. I could set up my own store but it would be through them and there is a monthly fee, but it looked reliable. But ideally I would want to have my own domain like spritelight.com. How can I go about doing this?