First, you'll follow the instructions in the PIVOT Tennis app that you download from the Apple app store.

Your PIVOT Tennis Kit consists of six sensors and a portable Wi-Fi unit, essentially a slightly larger sensor (it's marked as H, which stands for "hub").  One sensor clips onto your racquet like a vibration absorber and the rest of them are inserted into the chest harness, armband, and glove that you wear. 

The sensors track your playing arm, shoulder, chest, and racquet, and communicate that information wirelessly to the PIVOT Tennis app, which then both visualizes what you're doing and shows you how to improve it.