They pay you for your articles in two ways.
CPM - Yahoo! pays you for each article view on a sliding scale, the more views you generate the higher your bonus. To go over the first bonus level you need to have had 10,000 readers otherwise you have a standard payout of $1.50 a per 1,000 views.
They also pay you an upfront payment for some articles I have earned up to $7.50 for one article and that also carries a CPM payment schedule too. So every view can add to your income.
Try a Yahoo! Voices account it is free and you can write an article on any topic and licence it to them as part of their pay per view program.