Shaikh,
Open the \client\stemapp\themes\BillboardTheme\layouts\default\config.js and add a new place holder as shown below in lines 84-89 or if it an existing app that you want to add the placeholder to then you open the \server\[app #]\themes\BillboardTheme\layouts\default\config.js:
{
"widgetOnScreen": {
"widgets": [{
"uri": "widgets/Search/Widget",
"position": {
"left": 60,
"top": 10
},
"version": "2.1"
}, {
"uri": "widgets/ZoomSlider/Widget",
"position": {
"top": 10,
"left":15
},
"version": "2.1"
}, {
"uri": "widgets/HomeButton/Widget",
"position": {
"left": 15,
"top": 80
},
"version": "2.1"
}, {
"uri": "widgets/MyLocation/Widget",
"position": {
"left": 15,
"top": 120
},
"version": "2.1"
}, {
"uri": "widgets/Scalebar/Widget",
"position": {
"left": 15,
"bottom": 25
},
"version": "2.1"
}, {
"uri": "widgets/Coordinate/Widget",
"position": {
"left": 15,
"bottom": 5
},
"version": "2.1"
}, {
"uri": "widgets/OverviewMap/Widget",
"position": {
"right": 0,
"bottom": 0
},
"version": "2.1"
}, {
"uri": "widgets/Splash/Widget",
"visible": false,
"position": {
"relativeTo": "browser"
},
"version": "2.1"
}, {
"position": {
"left": 60,
"top": 53
}
}, {
"position": {
"left": 105,
"top": 53
}
}, {
"position": {
"left": 150,
"top": 53
}
}, {
"position": {
"left": 195,
"top": 53
}
}, {
"position": {
"left": 240,
"top": 53
}
}, {
"position": {
"left": 285,
"top": 53
}
}]
},