Unable to call a custom hook.

[sarfaraz.r1406]

I have created a custom hook. Made an entry in table and have linked the module to it. I am not sure from exactly where should I declare the hook variable. (exec=>(Hook)). From FrontController or from a custom method? Please help. Need to sort it urgently.

This is my mymodule.php file

(refer attachment)

mymodule.php