It is Sinterklaas not Sinterklass. The day of celebrating varies from the evening of the 4th of december till the 6th of december. It mostly depends on the tradition your family follows.
Santa Claus is an American adaptation of the Dutch/Belgium (catholic) feast of Saint Nicholas.
In Holland Sinterklaas is most often companied by black helpers called Zwarte Piet (sg) (black pete), there is no racist undertone in this although some really want that to be.

The legend says he saved 3 children from beiing eaten alive by a witch or something. And also, zwarte piet (black pete) isn't black because he's an African , but because he climbs through the chimeny to deliver the presents.