You need at least one flow element for the input and one for the output; additional elements may be required depending on the processes you want to automate.
Input and output: The most basic flow consists of two Folder elements, one for the input and one the output (see example below), but depending on the way you want to deliver your input and receive the output, you can select other elements, such as FTP Receive… (See Input and Output).
Processes: A number of flow elements allow you to perform processes, such as Merge PDF, Compress, ... See Processes: standard processes and Processes: Configurators).
To add a flow element to your flow