OK, so you've decided you want to set up a web based business, but:
1) Do you actually know what you want to sell?
2) Is your idea original?
3) What is your target market?
4) Do you have the time and money to make it happen, let alone successful?
5) If there's already other sites selling something similar, can you compete on price?
You've asked other questions on here about online and tv ads but you haven't yet got a website/app to advertise. You really need to concentrate on the small things first.