If you are executing a REST operation that requires a body, you can paste it into the Request Body input. So for instance, the creation of a volume. While this is a default workflow and that should be used instead of a custom REST operation, this is just an example.
Creation of a volume is a POST operation with a resource URI of /volume/<volume name> with a JSON body of {"size":"10T"}. So if I want to create volume called newvol-vro01 that is 1 TB in size:
If I want to create a volume named newvol-vro02 with a 1 GB/s bandwidth limit that is 10 TB in size:
The workflow logs the response: