Have you checked out the GDNative C++ example page on the documentation? I think it shows you how to get started using GDNative and C++ together with Godot.
If you are looking to make games with C++, unfortunately there is not a lot out there on how to go about it. The only resources I found on it was on a Godot QA question:
(Re-posting from this topic)
The answer from this Godot QA question has some links that may help you learn how to make a game with C++ in Godot.
There is also this page from the documentation on making custom modules in C++ If you want to add/extend the Godot engine itself.
As for the syntax, I do not really know. From what I remember, most of the functionality is exactly the same as it is in GDScript.
Unfortunately I do not really know of any other C++ resources than the ones I have added.
Hopefully this helps :smile: