how to write article for a blog or website?

If it's a general article website, I'd say it would be difficult to make money by spending AdWords money to collect AdSense money, especially by sending traffic to the home page where the ads would vary greatly based on what articles are shown.

If, however, you had some good articles about topics where the ads were well focused to the page, and the keywords for the page were fairly valuable, and if you could somehow come up with a good list of similar keywords that were fairly cheap to buy on AdWords, then you could do fairly well if you blend in the AdSense blocks so as to encourage clicks (not encourage clicks by telling the reader to click, of course, but by using some of the tactics mentioned by the Michael Cheney videos and other AdSense ebooks).

I'm not suggesting you go buy AdWords ads for very competitive phrases, I'm suggesting you buy AdWords ads that you can get in volume for a nickel, and send the traffic to a good article page that targets a similar topic, but will normally show ads that maybe the advertiser is paying a dollar or more for.

I would also suggest that you give the pages you target another monetization source, maybe amazon.com ads with your affiliate link, maybe a relevant ClickBank eBook or two, that kind of thing.Click Here-----! Write A Professional-quality Article For Fame, Fortune Or Web Traffic In One Day. Fail-safe Method That Any One Can Use!

It's not rocket science, but it's tricky, and you can lose money until you get it right. Once you figure it out, you can lather, rinse, and repeat until you're financially set.