Android :: How To Compile Helloworld With Android Source Code

I wanted to run a helloworld application with the AOSP and see it in emulator.[ Not through Android SDK setup]I followed the steps in http://source .android.com/source/download.html and compiled successfully the full code from / directory.I could see contacts.apk, camera.apk all applications apk in ~/ mydroid /out /target/product/generic/system/app. tried two things.1 - Went to /package/apps folder. Took a helloworld application( helloworld folder which was created in android-sdk), and copied a 'Android.mk' file from Launcher2 folder, kept my new name for application and placed the folder in packages/app folder and compiled at /. I couldnt see .apk file created for ~/mydroid/out/target/product/generic/system/app.2 - I changed the package name for Launcher2 in packages/app folder in 'Android,mk' file and compiled at root. I couldnt see a new apk created on the new packaged name under ~/mydroid/out/target/product/generic/system/app. tried several times with changes in activity names, application names in manifest.xml file. Nothing reflects.But it is sure, both helloworld, and change in package name is getting picked up while compiling. I could see intermediate classes getting created. ~/mydroid/out/target/common/obj/APPS/manifirst _intermediates/src/com /android/mani --> manifirst is like a helloworld which i created and run.~/mydroid/out/ target/common /obj /APPS /Launcher2 _ intermediates /src/ com/android/ launcher Could anyone please share the steps of compiling a simple Helloworld program in AOSP?