A BRIEF OVERVIEW
So the primary tasks to earn through Google Adsense are
1. To make a website if you don't have any. If you already have a website then to
justify is it ready to apply Adsense.
2. Sign up for Adsense
3. Placing Google ads on your website.
4. Driving traffic( bringing visitors) to your site and earn through it.
The primary tasks seem pretty easy. But earning through Adsense will not be as easy as it seems if you not follow the basic rules. The most important point is Adsense is no quick way to be rich. So if you make a hurry without a proper plan you can not make a success. Success to me means earning a minimum of 1000$ per month.
You can bring success to you by cost of your time. It will not come overnight. It can take few months or more. First few months you have to work on an average of 2/3 hrs a day. After that 2/3 hrs a week is sufficient.
So what you have to do first??
You have to make a website.
Before making a website you have to choose a topic on what your website will be.