Ruchira,
Not sure why you are not using the Web AppBuilder to do this configuration for you... Sounds like you are just taking the StemApp and deploying it to your web server. Here is what the json should look like for the coordinate widget.
{
"outputunit": "dms",
"spatialReferences": [
{
"wkid": "3857",
"label": "WGS_1984_Web_Mercator_Auxiliary_Sphere",
"outputUnit": "",
"transformationWkid": "",
"transformationLabel": "",
"transformForward": false
},
{
"wkid": "102629",
"label": "NAD_1983_StatePlane_Alabama_East_FIPS_0101_Feet",
"outputUnit": "FOOT",
"transformationWkid": "",
"transformationLabel": "Transformation Name",
"transformForward": false
}
],
"decimalPlaces": 3,
"addSeparator": false
}