My favorite brand of clothing is Donna Karan
Same here, she is such a great American fashion designer for making her brand.
Do you know when she started this designing
Well she graduated in 1966 and went to Parsons School of Design so technically she started designing around then.
It means she has been into this for a long time. No wonder her products are so fascinating 
She really has, since she began working right out of college for Anne Klein.
Did she have any co founder or someone helping her on this
Not that I know of, but Anne Klein seemed to really help her along the way, since she worked for her as an assistant designer.
That is cool. I know making great stuffs comes with help. Where was she born?
Donna Karan
Donna Karan (born Donna Ivy Faske; October 2, 1948), also known as "DK", is an American fashion designer and the creator of the Donna Karan New York and DKNY clothing labels.
Early life.
Karan was born Donna Ivy Faske to mother Helen ("Queenie") and father Gabby Faske in the Forest Hills neighborhood of the Borough of Queens, New York City. Her family is Jewish. Karan's mother had been a model and had also worked in designer Chester
Helen Yarmak
Elena Davydovna Yarmak (; born 6 July 1949), known professionally as Helen Yarmak, is a Russian fashion designer and creator of the Helen Yarmak fashion house.
Having been born in Kiev she graduated from Kiev State University and then worked at the Cybernetic Research Institute. She started designing and making clothes in the early 90's. House's first models were labelled "Helen" when in a little while "Helen Yarmak" brand appeared and became popular all around the world.
Helen is a member of