Please help - setting up home wireless network

I'm trying to set up a wireless network at home but I don't know how to do it.

Here's what I have.
Two laptops with wireless network cards.
One stationary computer with a wireless network card.
One wireless router.

This router is something I could borrow from work but I don't know anything about it.
It's a D-Link.
Vertical design. Seems to have two small antennas.
There are five connectors which I'm guessing one is the in-data and the other four are out-data.
I have a power connector for it so the power is on.

All my computers can find networks in the area so I know the wireless cards are working.

So how can I connect these computers in a network and share the internet connection?

Thanks a lot for any help!