On package installation, everything should be ready to use. However, if you have any problems on JCE plugin, you should check these steps.

If you have deleted or you're not using the Default profile, you have to manually add the J4Schema button on JCE editor. To do that, you have to go in JCE Administration » Edit profile » Features tab and drag&drop the Google button.

As last step, you have to disable the "Cleanup HTML" features, since we're adding non-standard HTML tags, JCE sees them as errors and strips them out from your articles.

You can disable it from JCE Administration » Editor Global Configuration.

Excellent! You're ready to start!