Dude, seriously. It's simple. He has a house, right, and in his house, he has multiple rooms. Got it. One of those rooms is his bedroom. Unfortunately, his router (surprise, he has a router) is on the opposite end of his house. So... instead of passing an Ethernet cable across his house, into his room, he uses his LAPTOP, which receives the wireless connection that is sent from the router. After that, he plugs an Ethernet cable into his laptop. After that, he plugs the other end of that cable into his tower PC. Following so far? Gooood. Now, on his laptop, he uses a feature in Control Panel. With this high tech feature, he allows the laptop to BRIDGE the wireless connection of the laptop to the Ethernet cable. Wow. From that point on, the PC detects the connection as a wired connection. And then, guess what? His PC can connect to the Internet via that shared connection!
EDIT: His laptop is in his room...