This is really difficult, and I have found many C2 tutorials are out of date (as well as some of the C2 google plugins). Not to scare you off but it took me a solid two weeks to get my game up and running. I will walk through the process really quickly to give you some starting points to start searching. Google is your friend!!
You will first need to export your construct project with "cordova". start there.
Then you will have to build the actual APK. I know some people use something like CocoonJS but I have an adobe creative cloud account so I use PhoneGap to build APK's.
It should be as simple as pack all your export files in a .zip. Upload that .zip to phonegap and it compiles an APK for you, you can test on a mobile phone.
To publish on Google PLay you will need to sign your APK's. you will need to download the Java JDK and run a commandline tool to generate a .keystore file. This can also be uploaded to phonegap to sign your APK so phonegap compiles a release version of your APK which is needed by google to upload it to the store.
In between you will have to alter the config.xml file in your construct export to accommodate changes you would like to make to for instance your IAP or google play plugins. Also I have found phonegap doesn't automatically build an ARM ready APK which is needed for most mobile phones.
As you can tell, google it! I am writing an elaborate tutorial on my site. But due to the extend of it it might take a while..
Hopefully I have at least given some points to start you off...