A brief explanation….
The first thing you need to do is read this. It will explain how to get your certificate and private key to build the Android app in the first place because without them you cannot build it.
http://www.genuitec.com/mobile/docs/buildandroidapp/buildandroidapp.html
Once you have the app built and tested and I am assuming you wish to publish it on Google Play and not host it yourself.
You then need to join the Android Developers club… US$25.00 Which gives you access to the Developer Console which you need to submit your apps.
You will need at least 2 screenshots, (jpg or 24 bit png files), you have a list of sizes to chose from, plus you need a high resolution app icon (512×512 32 bit png), a feature graphic (1024×500 jpg or 24 bit png) and a promo graphic (180×120 jpg or 24 bit png).
That’s not including all the icons 36×36 48×48 72×72 96×96 and the 4 start up screen images needed.
Once you have all that together, fill in the required info and upload the .apk file that mobione has built for you.
It’s somewhat easier than Apple and there is no review time, once you publish, it takes a few hours to go live, I am sure they actively check the submitted apps for quality though.
I wish you luck.