You will need a router, not a switch. Your ISP usually only gives you one IP address. Your will need a router with DHCP to connect multiple devices.
Just plug the cable in. An icon should appear in the top right corner, indicating it is connected. Provided your router is connected to the internet, you should have internet access automatically.
plug in your ethernet cable, or connect to the internet in any other way, then you should be able to connect by opening the steam application.
Ethernet? the question isn't completely clear, but that's what I think?
Ethernet splitters are great if you want two people to connect to the same Ethernet port. Home networks should be as long as all the computers in the network are hooked up to the internet, not necessarily the same port.
Maybe the ethernet cable is not your problem. Ethernet cables are available everywhere and they all should work for the PS3, PC, router, modem, etc. ethernet ports are one way and are either in or out. The spot on back of the PS3 to connect an ethernet is a standard size and is meant to connect to a modem or a router or it will not work.
NAS
Ethernet and Star
Your Ethernet cable should have an RJ-45 modular connector on each end of the cable. Connect one plug in the RJ-45 slot/connector in the back of the desktop unit, and connect the other end to a switch, hub, or router.
If you have an ethernet cable plug it into the modem and they should be connected. My Modem is connected with a router to the rest of the network and with the internet modem and is both wireless and wired
You need a ethernet cable. First go to Network Connections in the control panel. then highlight the wireless adaptor and ethernet adaptor right click and click "bridge connections" then you should be able to access live on the xbox with the ethernet cable in the xbox and your laptop have a look on youtube there is a few vids up there.If you want wireless, you need a wireless adaptor. They're available on eBay.
It's up to you. If you do not mind cables laying around go with wired connection. If you prefer not to have cables you should use wireless.
It shouldn't matter which port you use unless it involves a network switch.