How does lightning network work at the actual level?

So I tried to understand the basic functions of lightning, but theory together Practice. This is my meaning.

The theoretical introduction begins when Alice and Bob want to pay each other without settlement of chain every time. so OpenEven if Charlie and Alice want to exchange SAT, they can use their existing channels for BOB without opening their own channels.

But in reality, what I do is to use my aqua wallet. Create a invoice Or pay the merchant invoice. There is no concept of channel or user level.

So I have to solve the gap between the other two worlds. For example, Suppose I book a vacation in Travala and they show me. invoice Pay 800,000 SAT. So when I pay using Aqua wallet channel And is it like that? Do you have any resources to learn about this?