For this First thing you need to have a Web site or a video Content.The content you create may be the text or video, it is suppose to be unique content ,make sure to create it by yourself not to outsource it.Ad sense will never approve a duplicate or copied content.If you do already have Ad Sense account and in order to increase your revenue if you spam the content then there is a high chance of your account getting blocked
Sites that you can have for adding Ad Sense:
Apart from these you can have more customized sites with great content.
Connecting Ad Sense to You tube.
How to get an Ad Sense account.
In order to get your Ad sense account activated certain task needs to be completed.
How does Ad-Sense look like in future concerning this thought there are many ideas springing up another question tagged to same is how the system will change opposed to what it is currently.
Looking at Google search engine itself from few years back then to now it is clear that there targeting algorithms will become powerful and better then they are now.Advertisers now have to struggle to manipulate their content to allow high paying keywords unless it is actually appropriate to their content
Participation in Ad Sense is free.
Google will pay you for clicks
Hope this blog was informative to at least few of them out there.