...and go straight to business. Find a host that supports one of the open source e-Commerce systems. They usually have good destructions on how to upload and configure, and good communities to help you with questions and problems. If its open source, you can look at the code when you get a bit more confident and try changing it (not on your live site!) to get the effect you want. In my experience, the open source e-commerce systems are good, but a bit rough around the edges when you first download them, probably to differentiate them from a 'commercial' edition. You'll learn a lot about fixing a website when you start!

I'm sure not every successful online entrepreneur can write HTML that will pass the W3C Validator! I'm equally sure there are a lot of expert coders making not a lot of money out of the 'business' they spend their lives fiddling with.