If you are not connecting using a router or a hub, you will require a crossover ethernet cable, which is pictured by DeveloperX is his previous post. By connecting both computers together, it will work exactly like how it will work in connecting through a router or a hub.
Making a folder shared will enable other connected computers in the same network to access its contents. For example, if you share a folder on your notebook, the desktop PC will be able to access the contents of the shared folder on your notebook.
Typing the IP address of the computer that has the shared contents on the web browser will access it's shared contents. For example, if your notebook IP address is 192.168.1.100, then you type "\\192.168.1.100" on your desktop computer web browser to access your notebook's shared contents. In this way, data can be transfered to and fro from computers to computers.
Regarding with sharing the wireless internet connection, it is unethical and wrong to connect and tap onto other wireless networks without permission. It's the same as Unauthorised Access, and Network Hijacking, which can be penalised and charged in court. But assuming you have the permission and authorised to use the network, you will need to share your wireless connection on your notebook. You can do this by configuring the network settings of your wireless connection and set it to be shared by other computers. In this way, the desktop computer connected to the notebook through the wire will be able to access the wireless internet, with the notebook as the middle-person. Both notebook and the desktop computer can now surf the internet at the same time.
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