To use Segment, a developer needs to create a source in their Segment console, which is a website or application that sends data or information. A Segment account is required to follow along with the process of creating a source. To make a source, one can click on "Sources" and then "Add Source", selecting JavaScript as the source type, and providing the website URL. Once created, the developer will receive code to include in their website's code, which allows them to track actions and send data from their source. The Segment console provides various functions such as `identify()` and `track()` to record user traits and actions, respectively. With a Segment source set up, developers can send data to destinations for analysis and further use. Additionally, Segment supports adding mobile applications, Cloud Apps, and other types of sources to track data from various platforms.