if you are interested in decompiling Android apps on windows for educational purposes,you may want to give these applications a look:
1-Real APK Leecher: for downloading android apps on windows OS,please follow the instructions strictly,otherwise,it will only cost you unnecessary time of research,please enter device ID of your android kit,gmail user/pass associated with the device , and then try to download the apps and it will work perfectly.
2-dex2jar: a command line tool for converting DEX files(special compiled java classes of Android) to jar file.
3- dj-gui: convert the jar file to “readable” java code,please take into account that Android does some optimizations on the code before packaging it.so the code will not be 100% the same as the original one. e.g all of the constants will be converted to their corresponding values.
just convert the apk file to .zip,and you could see the app resources,save them,etc..
for more information please refer to: