Page layouts define the look and feel of a set of pages by styling page fields and web part zones within the common elements ...

Page layouts define the look and feel of a set of pages by styling page fields and web part zones within the common elements of a master page. You can use the network drive you mapped earlier to edit your page layouts using any HTML editor. To preview your page layout, click on its file name or status. While previewing your HTML page layout, use the Snippet Gallery to get code snippets for SharePoint functionality that you can copy and paste into your HTML file.