How do you connect a laptop to a television?(ten points)?

Okay so I have an HP laptop. I also have a 32 inch Sony HDTV flatscreen. LCD. I have already bought the cable and sound cable so I can make the computers screen show up on my tv. I bought it at radio shack. I plugged one end to the computer, the other to the tv. I know its correctly plugged in. My concern is, its not working. Do I have to go to certain setting on my television to make it show up? if so, what do i do? Please help me and thanks. Ten points