Well you'll need to purchase Cranberry's plugins from the Scirra store.
-Install Chartboost plugin into Construct (just drag the Chartboost plugin onto the menu area of C2, then restart C2).
-Open an account on the Chartboost website. Set up your game and set up an advertising campaign within the Chartboost dash.
-Back in your C2 game project, add the plugin to the game. In the Chartboost plugin properties add the App ID codes from the Chartboost dash.
-You'll need to make events in your game project to call your ads at the right time (for example, when player dies x times, call an add).
-Then in XDK you'll need to add a third party plugin and enter the git url:
I think thats it, hope it helps.