How to Make Piles of Money Using Instagram

It’s the first day of class at Instagram. Students check in at two security desks and sign non-disclosure agreements before heading up to the photo-sharing app’s Manhattan offices. The 20 or so guests, almost entirely women, stride past the cluttered workstations of Facebook Inc. engineers and into a conference room.

In attendance are executives and marketing managers from various fashion and beauty companies. Birchbox, a seller of makeup and bath products that’s raised $100 million and jump-started the subscription box craze, sent six. Another group from Madewell—J.Crew’s sister brand—sits up front. Big names from denim brand Ayr and Soludos take their seats. Even famed designer Cynthia Rowley makes an appearance, along with the president of her label. So does her daughter, Kit Keenan, an Instagram influencer who has been featured in Teen Vogue and Refinery29.