To create a new Publication, click on the publisher app open it up. When you see the following screen pop up, click on the template labled blank . You can choose which orientation you would like, Potrait or landscape or use one of the other page sizes.
Templates
Microsoft Publisher comes equipped with hundreds of premade layouts and cookie cutter templates you can use for guidance, ideas, or inspiration.
To use the templates Just click on the template you want to use to open it or you can use the search box to find a specific template.