How can i sell my articles in digitalpoint site?

From what I've seen, DP specialises in domain names, ebooks and some other stuff in their marketplace. Articles and site content tends to be bought to order (all those WTB posts in their forum). I guess you could post in the Content Creation forum and offer your already-completed work. Alternatively, check out Constant-Content. If you can get through their editing guidelines (which really aren't strict), you can put your articles up for sale there at a price of your choosing. I've used it to sell content in the past - a very good, completely reliable site, though they take a fairly big cut of the proceeds (so set your prices accordingly).