There are no hard-hitting rules for that. And this is both a good and bad part. You don’t need any kind of experience to be an author. If you can write decently, you’re good to go.
Your question has answers in two parts. First, publishing your book; and second, becoming an international best seller.
Today, publishing your books has become easier than ever. And the best part is it doesn’t even include any expense and you can do this fortnight.
There are two ways of publishing your book:
· The Old School Way
This is how the books have been published traditionally. You contact a publishing house directly (or through agents). Submit your proposal to them. Whether you’re doing this directly or through agents, there will be lots of rejections. For many, your (amazing) book won’t even be qualified for submission. So you must continue submitting your book’s synopsis until someone finds it interesting.
Even when accepted, getting published isn’t guaranteed. You might be asked to make some edits which might not appeal the creative you.
Once you and a publishing house are on the same ground, all the legal ends will be met. And your book will be out in the market the following months.
This is a time-consuming method and even cost high. You will have to try a lot harder here. But one good thing is you’re going to get professional assistant, which would likely improve the chances of your book’s sales.

· The Digital Way
Also called self-publishing, more and more new authors are going this way. It’s simple, quick and cost-effective—all thanks to Amazon and its Kindle Direct Publishing (KDP). Once you’ve finished writing, editing and formatting your book, you can hit the Kindle store and make an account there.
There will be few steps there and then you’ll be asked to upload your book. Once your sales page is complete you can hit the publish button. After few days of review from Amazon, if everything goes right, you’ll now be a proud published author. All you have to do now is market the book yourself and grow sales.
Amazon also offers Print on-demand service. Meaning, they print your book in their own facility. You can design your cover for the hardcover, format the book accordingly and then send the book for printing with just a single click.
Now the second part of your question… How to become international best-selling author?
It’s quite simple! All you have to do is publish quality work. Once a handful of people start liking your work, words-of-mouth marketing will catch up and your book will get decent recognition. Of course, this is just to say in general. In reality, things aren’t this simple.
If you have a publishing house working with you, the marketing of your book becomes much easier. They arrange for most of the thing—press releases, meet-ups, social media campaigns and so forth. So the chances of becoming an international best-seller become easy.
If you’re self-publishing, you will have to market your book yourself. You can hire marketing professionals for this though. With no experts’ assistance here, becoming a best-selling author seems a distant idea.
Note: how many copies you must sell to become an international best-seller varies from list to list and countries to countries. You goal is to sell as much copies of your book in the shortest time.
Approximately, to become Amazon’s best-seller, you must sell 3,000 copies in the first week. To get a spot on The Wall Street Journal’s bestseller list, you need to sell 3,000 copies. For NYT Bestseller list, you will need to sell 9,000 copies.
Hope I answered your question. All the best!!!!!!