Snippet showing how the layout is created, and how we setup the regions which are nodes in the layout's template

layout.js

var LayerListLayoutView = Backbone.Marionette.Layout.extend({
  template: "#layer-list-template",
  //define the regions using selectors for nodes
  //inside the layout's template
  regions: {
    layerListRegion: "#layer-list",
    basemapRegion: "#basemap-list"
  },
  events:{'click #layer-list-close':'closeView'},
  closeView:function(){
    Viewer.vent.trigger('View:LayerList:Hide');       
  }
});