"Congratulations, you're a manager! After you pop the champagne, accept the shiny new title, and step into this thrilling next chapter of your career, the truth descends like a fog: you don't really know what you're doing. That's exactly how Julie Zhuo felt when she became a rookie manager at the age of twenty-five. She stared at a long list of challenges--from hiring to firing, from meeting to messaging, from planning to pitching--and faced a thousand...