Source is a component that extracts data from a data source and starts the data flow. Source is the very first component you should add to the diagram.
After you have added Source, click it and configure its details — select a connection to get data from, select and configure the action to perform in order to obtain data and map its parameters if needed. You can also give Name to the component displayed on the diagram.
Source component has one regular output and no input. Its output returns the data obtained by the selected action.