How do you advertise online?

Seriosuly, I have tried a lot, wasted a lot of money and can't get anytihng. I am on the edge of a bleeping stress meltdown. I have a good product, at a reasonable price. So HOW do you advertise? email blasters do not work neither do scam companies that charge you for like 5,000 hits. HOW do you do it? Its an ebook if that helps. A VERY useful ebook. So seriously how do you properly advertise your own product?