Connect PC to notebook as possible?

I want to copy some files. What is the easiest way to do it without additional storage media.

Simply connect to each other with a network cable? Then what do you have to do?

I have an O2 Homebox 6441, isn't it also possible to connect both devices to one another? When I plug in both devices, I have internet over the network, but I can't access each other. Would be nice if someone could help me.

Almost every notebook has Wi-Fi or bluetooth. Another adapter in the PC, then you can start

You have to share the desired folder in the network, then you can use this folder with the other computer.
Both computers must be connected to your router (whether via. WLAN or LAN doesn't matter).

Here Microsoft explains it:

https://support.microsoft.com/...-a-network

If both devices are connected to the home box, you already have a network.

then all you have to do is to release a folder in the network on one side, then you can copy the files from A to B.