Set up Xamarin  in your visual studio.  follow the steps here

Create a blank android application in visual studio

Now you can check the solution explorer its contains the following folders, its pretty similar to the android eclipse blank application. here the view/layout file extension is .axml and the main activity file extension is .cs instead of java obviously its .Net so it should be like that.

here in c# we are invoking the android interfaces so you wont see much difference if you developed android application using java.

by default android emulator available if you configure xamarin in visual studio you can use other emulators also,I am using genymotion emulator for faster performance.

So I am going to build first application it has the code available to display the hello world functionality.

one button and on click it shows the count.

You will get the .apk file for your sample application inside the corresponding bin folder.

The sample code is pretty clear so not giving any explanation to that.

so lets start creating your apps.

As discussed in my previous post(Read), you can create mobile applications for all major platforms using c# and .Net
There are 2 IDE's available for Xamarin development, you can use Visul Studio or Xamarin Studio
Xamarin studio come along with Xamarin installer if you are using mac this your IDE, for windows users you can download the Xamarin for visual studio from below link.

Download Xamarin
Xamarin developer version is now free along with visual studio 2015.
Download :Visual Studio 2015

If you want you can use the different emulators,  by default along with Xamrin you will get android emulator, but its little bit slow.
Here is one third party tool you can use for android emulators, It will support from windows 7 onwards.
Genymotion Emulator : Downlaod

Another good tool is Hyper V Emulator : Download but there are some compatabilty problems with windows 7 so those are having windows 8 can go with this emulator.