What piece of networking equipment do I need?

[Beano]

Right now I have 3 computers in my room, which is soon going to be 4. What's the piece of networking equipment called that enables all these to connect to a wireless network via one wireless adapter thingy? Sorry if I'm not making any sense, its really simple and I should know this but I've completely forgotten the name of it.

Thanks to anyone who can help, this is rather important.

[NaDe]

Is it some kind of program or hardware ?

[Beano]

It's a piece of hardware.

[NaDe]

It's a piece of hardware.

Do you mean an router where there are multiple ethernet plugins ?

[Omniscient]

You want a wireless router.

[Beano]

Do you mean an router where there are multiple ethernet plugins ?

Kind of. I already have a wireless router, I just need the piece of equipment that will allow me to connect 3 or 4 PC's together to share the same wireless thingy. I honestly have no clue what it's called anymore, I should know this!

You want a wireless router.

I already have one. If I get another one, will that be able to connect to my existing one?

[Krueger]

Do you mean cables ? xD
I dont know either mate

What do you whant to do exactly share your networks with the four pc's ?

[Beano]

Right I'll post how things are set up which may make you understand me a little better.

Upstairs:
PC1 - PC2 - PC3 - PC4
|_____|_____|____|
________|
Wireless Thingy?

Downstairs: Wireless Router connected to internet.

So I need to know what the 'Wireless Thingy' is actually called. Omniscient said I need another wireless router but I connected one up and couldn't find a way to connect it to my wireless router which is downstairs.

[Beano]

Bump, can anyone help please?

[Camgaertner]

I already have one. If I get another one, will that be able to connect to my existing one?

I believe what your trying to say is, you have multiple computers in your room, but only one Ethernet plug? You want to get a router. I have one in my room for this purpose.

EDIT: I have this one