What do I need to do at the layout/editor page?

This step will show you your spreadsheet contents already styled as you had at the spreadsheet. You only need to select which cells will be 'inputs' at your form. Click on one cell, and select at the right panel 'input cell'->input type (number, text, combobox, etc..). You can also add any style here to any cell, change texts, and adjust columns width.