1. When you add Google ads to your website with your unique publisher number, you make money every time visitors click on those display ads.
It calls pay per click advertising.
2. To add Google ads to your website, first you need to register with Google ad sense and add your web address or URL. then Google staff will get back to you through email in regard to approve or disapprove your ad sense application.
Read Google term and agreement before you apply to make sure your website comply with their rules and regulations.
3. Once Google approve your registration as a publisher, Google will issue your ad sense publisher number, which is a unique number to identify every publisher. Every time you create a Google ad sense code, your publisher number will be automatically included into the ad sense code.
4. You can choose from different kind of advertising venues, such as image only, image and text, text link only, search box, video streaming ads, etc. You can choose the size of the ads to display on your website as well.
5. After you create an ad, copy and paste the ad sense code to your website. If you create your website using WYSWYG (What you see is what you get software) or using website templates, You need to go to HTML source to add those ad sense code. Repeat for every pages where you want Google ads to appear.
6. Preview and update your web pages and Google ads should appear on your web pages in few minutes, sometime it appear in instant. Google ads are contextual ads, meaning it will display ads that relevance to your website content.