Hi!
First of all, have you bought an audio cable yet? If not, you need to buy one
Also, do check if your HP laptop has an S-video port as well. That should coincide with your TV's S-video port.
Now if you have both of these, all you need to do is buy an S-video to RCA adapter. That should do the trick.
If you're not too sure where to buy such adapter, you can check out the websites of Best Buy or Radio Shack.
Hope this helps! Let me know if that worked for you