add webmap from JSON instead of ArcGIS Online in Viewer.

index.html

<script type="text/javascript" src="./config/webmap.js"></script>
<!--existing tag-->
<script type="text/javascript" src="//js.arcgis.com/3.10/"></script>

main.js

//...
this._createWebMap(customWebmap);

webmap.js

var customWebmap = {};
customWebmap.item = {
  "title": "Soil Survey Map of USA",
  "snippet": "This map shows the Soil Survey Geographic (SSURGO) by the United States Department of Agriculture's Natural Resources Conservation Service.",
  "extent": [
    [-139.4916, 10.7191],
    [-52.392, 59.5199]
  ]
};

customWebmap.itemData = {
  "operationalLayers": [{
    "url": "http://server.arcgisonline.com/ArcGIS/rest/services/Specialty/Soil_Survey_Map/MapServer",
    "visibility": true,
    "opacity": 0.75,
    "title": "Soil Survey Map",
    "itemId": "204d94c9b1374de9a21574c9efa31164"
  }],
  "baseMap": {
    "baseMapLayers": [{
      "opacity": 1,
      "visibility": true,
      "url": "http://services.arcgisonline.com/ArcGIS/rest/services/World_Terrain_Base/MapServer"
    }, {
      "isReference": true,
      "opacity": 1,
      "visibility": true,
      "url": "http://services.arcgisonline.com/ArcGIS/rest/services/Reference/World_Reference_Overlay/MapServer"
    }],
    "title": "World_Terrain_Base"
  },
  "version": "1.1"
};

Sir , actually the problem is this template , this is responsive Js Template of basic viewer , now my problem is what , in defaults.js there are webmap id , i want own map services with json ,
thanks for help .
http://www.arcgis.com/home/item.html?id=b17113eb9535427db477777f86f25d63
this is the viewer