Read this http://forums.pocketmine.net/thread...plugins-from-amaibeetroot-to-zekkoucake.3612/ It must helped you to porting your plugin
You will want to use pocketmine\event\player\PlayerInteractEvent. Health isn't yet implemented in 1.4 so you won't be able to anything with heal().
sorry if this is off topic but where do you find functions in the doc. and how do you do the healing function?
On the documentation page click the "Classes" tab. It should come with a list of namespaces containing different files/classes. Btw, when functions are part of an object it's called methods (with Javascript as an exception).