The columns from a template register view, come directly from the fields on the form. The rows, then just represent every individual form that has been submitted.

Therefore, to create a register, you'll need to set up a template with the relevant fields (that you'd like to have as columns).

As an example, below is a register view for a Excavator Inspection Checklist.

If we then open the form, we can see the fields exactly match the columns from the register view. This is where the data is being drawn from.