You can add a new custom page layout made up of multiple rows with your own choice of column arrangements.
Click the button "Add row" to add a new row, and use the drop-down boxes to choose a column arrangment for that row. The thumbnail image gives you a preview of your new layout.
Once you are happy with your design, click the "Create new layout" button to add the new layout. Your custom layout will be created and selected. Click the "Save" button at the bottom of the page to save your choice of layout for this page.
Your new layout will be available to you in the future under "Advanced options" when you are editing your page layout.