If there are tasks that you want the Workflow to perform and they are not available in the list of workflow activities, you can create your own activities from the Workflow editor window and use them in your Workflow. When a custom activity is created, you can re-use it in any existing or future Workflow as it will be part of the workflow activity list of the CommCell.
You can create an activity based on a user-defined script, a user-defined command, a user-defined XML operation, or a user-defined HTML client operation, with custom inputs.