First what you have now?
Desktop pc and a broadband internet... what kind? Cable or DSL/ADSL?
How do you connect your desktop to the broadband modem?

Basically, you need a router (wireless access point router)
Check your laptop.. does it have a wireless adapter inside? newer laptop usually have a wireless adapter.
Then you may also consider other device in your home that might interfere with the Wireless signal.

and many more information needed to help you.

try to search the forum or read this: