So, I am new to cloud-foundry that's quiet evident by the question title but I tried to search a lot on the internet and could find a lot of distributed information i.e.
CF is cloud platform where you can publish your apps (web and mobile), no practical demonstration of how to do what and a basic setup for a newbie (probably i couldn't find).
CF is a free service where you can write and publish your web-services via Node.js and MongoDb.
But what I am really looking for is answer about how can I migrate or deploy a native mobile app i.e. an apk file on cloud foundry so that a user can download some cloud foundry client on his android smartphone and run the same.
What if I have made and apk or native android app ground up and I want to utilize the capabilities of cloud-foundry to release it to the users.
How much work is pending at my end and what ?
I apologize as I do not understand exactly what you're trying to do here, but if you just want to be able to upload and distribute some static files (i.e. your APKs), you can do that quite easily.
There is a "Hello World" tutorial here which shows how to push a static HTML file. Replace that file (or add additional files, everything in the current directory is uploaded) with your APKs and you should be able to distribute them via Cloud Foundry.
https://docs.cloudfoundry.org/buildpacks/staticfile/index.html#sample
Hope that helps!