Hello and
to the forums.
To be able to share an Internet connection you are going to need a router. Each ethernet cable will go from the router.
If you are finding that you need more than 8 ports then you may want to add a switch after the router.
Run one ethernet cable to each room. (More if you want extra sockets).
You can use ethernet for other uses such as phonelines, sending video signals and audio but they are best used for data.
If possible try and route your cables away from mains electricity cables.