You must have at least 1 test case.

You can open the test case panel from the test case issue:

To add a new steps click "New step" or press tab from the last expected result text area:

You can use an existing test case as a step by clicking "Call to test":

Select your test from the list and click "Add":

You can also add a new step from the top context menu:

You can add a precondition to your steps from the context menu:

You can add the step data column to your test case steps from the context menu:

To generate steps quickly you can use AI, click here to learn more.