As general rule, any product, including e-book that you plan to market in online business need to be put in a way that people can reach to the product when needed; in this case, when people interested and buy the product. It can be e-book with rich contents; a guide or information of the business itself, a health care guide, how to lose weight techniques or even personal experience of success in publishing, tips for website building, developing managerial skills, and so on.
In this information technology era, people always look up from the internet to seek whatever info they need. And what this have to do with e-book?
The answer is: when you need information online, you will start 'google' the net and looking for the answer to your question. This is when the e-book will play the part, helping people with interest on the subject they are looking for.
In order for your e-book to be reachable, marketing strategy need to be plan and without it, you won't be able to sell your e-book as people don't see you product.
And here comes the advertising parts!..
Advertising your e-book play a major role in determining the success of e-book marketing business.
There are many ways to promoting your e-book product, some need your own times, and for some others will go for paid advertising such as Adwords.
Adwords can help to advertise your product, but you need to spend some amount of money to pay for this service. Success rate varies according to how you advertise your product..more info regarding Adwords here.
For me, writing articles can be somewhat rewarding in promoting your e-book products. People will look up for you if you are a good article writer. At the same time, good article writer can also make money writing article to publisher who in return of getting the publisher's product reviewed, the writer himself can promote his own e-book. It's a win-win situation.
You can look up this link for some useful guide on article writing.