Having Trouble to Code Product/Plugin for vb4

[Meister2017]

Hi,

I have a friend of mine that was running vBulletin 3 but now upgraded to vbulletin 4.
He has a custom for him made Plugin for vbulletin 3 that was made long time ago and now does not run in vbulletin 4 anymore.

I personally did not have written a plugin for vbulletin until now because i am more into wbb from Woltlab.
I just run a vBulletin 3 with some Plugins and Templates.

So he gave me access to his vbulletin and Plugins.
I looked at the XML File but i can not figure out how it works.

I see with the XML File there are new Templates und Hooks created BUT i cant figure out the following:

Where is defined that Hook A is loaded in File B on location C.
i want in global.php to load the hook under <?php for example how do i do that? How do i tell vbulletin that i want to do that?

Same For templates, how do i define that i want to load template a in template b on location c?

I really do not know where this is defined and how vbulletin knows when installing a plugin where to put the hooks and templates in.

Maybe someone can help me?