What is a Website (adsense)? - We are talking about creating a website and placing adsense ads on it.

How can I make money from a Website? - By using adsense to place ads on your site, you can make money each time sometime clicks on these ads.

How much money can I make? - Depends on how much traffic you get and the subjectg matter of your ads. Some subject matter pays higher per click than others.

How much time do I have to invest in it? - The time to open/develop your website, and the time to update it regularly.

Does it cost anything to sign up? - Some websites are FREE, while others cost money to start up including your hosting account, and domain name.