The document provides an instructor's manual for a chapter that discusses building an e-commerce presence through websites, mobile sites, and apps. It outlines the key teaching objectives which are to discuss the process of developing an e-commerce presence, explain how to build an e-commerce site systematically, describe considerations in choosing software and hardware, and identify factors in developing mobile sites and apps. The chapter then covers topics like envisioning an e-commerce strategy, outlining the development process, selecting platforms and tools, optimizing performance, and creating mobile experiences.