How can you connect to a network using a laptop wireless?

Basically, I brought a laptop ( Advent 5612 ) and its a wireless connection to the internet and my brother has a PC and his network is called Belkin so I clicked on it and it said I needed a pword. He said he didn't add a pword. There's is also others to choose (next door neighbours internet) but I also need a pword. Is there any other way to connect to the Internet?