Adding a Layout is simple clicking on the Layout button and a new layout will be added.
When adding a layout, it always adds a layout based on the previous layout. So for example in the screen shot Layout2 contains only one page because Layout1 contains only one page. If Layout1 would had two pages, Layout2 would also have two pages.
Each page can be setup via the Producer Help - Page Setup window as described in that section of this Help file.