How to explain and show a new feature in a website?

So, there is this website with news and other things, like the weather, horoscope, etc.. And there will be a new service where some news will be prime, the user will have to pay to see the article. I want to make something to introduce this new feature to the users, and I was thinking a coach mark, the first time the user enters and sees an article, it pops up a dark layer explaining what it is, and it doesn't appears again.

I wanted to know what are your opinions on this and if there is a better solution?