Like SNM recommended, it would be best to locate a breeder who already works with harlequin Dutch (if they exist?- I am not sure of all the colors of Dutch).
Breeding a color like harlequin into Dutch by crossing a Dutch with a Harlequin (the breed) will not produce harlequin-marked Dutch rabbits right away. You have to have an extensive knowledge of how the harlequin gene works and how Dutch patterns work to begin a project like that. Marked breeds are tough!