How to use a hook?

[محروم.كوم]

<div>Hello,

Instead of editing a template every time i've done an update, I would like to use the hook system so this is done automatically. But I'm not sure how I can use this system.


For instance, let's say I want to include some HTML at this hook: $template_hook[postbit_user_popup]

I would also would like to use the __DEFINE_LIKE_SHARE__