Could anyone tell how to get the tracking server for my mobile app which needs to mentioned in the config json file.
You can also use the Mobile Services interface (http://mobilemarketing.adobe.com) to download the SDK for your specific application, and the .JSON file will be preconfigured for you with all of the required settings for your report suite.
Normally you will use the tracking server you use on websites (s.trackingServer in your s_code.js) ... If you have secure mode in you app you have to use the s,trackingServerSecure ...
You must contact ClientCare or your Adobe Account Manager