some people here are confusing Google AdWords and Google AdSense. So do you want to advertise on Google ? then it's Google AdWords, and you can advertise for other websites than yours, you don't need your own.If you want ads displayed on your pages (and earn money when people click on them), then this is Google AdSense. You can open a blog at
http://www.blogger.com and apply for an AdSense account. Post some content first. No need to have a website too.AdSense and AdWords are 2 different programs.AdWords are for advertisers, AdSense for publishers.When you see Ads on Google pages, these are AdWords (search network), but these same ads can be displayed on your pages, therefore they are AdSense (content network).In their AdWords account, advertisers choose if they want their ads to be displayed on both network or only one.You can apply for AdSense from your blogger account. But as I said Google approve websites or blogs with content. If you build a website with only 1 page and ask them to approve your website, they won't.So open your blog, write a few stories and submit it to AdSense program.Read the rules and follow the rules.