How to start up your own internet business?

I would love to set up my own business selling products but I don't know where to start. I've got a few ideas in mind of what I would like to sell but I don't know how or where to start! Im only 17 and therefore money is probably going to be my biggest hurdle but there is so many people out there who have made their first million before they're 18 and I would love to give it a shot! Thanks :D