You want serious advice, don't ask in PC world, especially from some supposed computer salesman who clearly isn't good at IT based on what you've just said.
Setting up a home wireless connection in most cases is quite straight forward.
First you need to get your self a cable compatible wireless router (It must
not have an inbuilt ADSL modem. There are recommendations elsewhere on the board. Personally I like the Linksys WRT54G series which oddly enough pcworld do flog
Setup is straightforward.: Power down all computers and the modem. Connect the supplied ethernet lead between modem and router. Connect your existing ethernet lead between router and current PC. Power on modem, let settel, power router, let settle, power PC. That's your wired network running.
The manual with the router will tell you how to get the wireless going, but again it's not complex. Using Internet explorer on your wired PC, browse to the setup pages of the rotuer, ofter
http://192.168.1.1. Log in as the admin user (good idea to change teh default password), and then got to wireless settings. Give your wired network a name using the SSID, and setup WPA encryption (stops others theiveing your connection) entering a password. Activate. The laptop should now be told to search for a wireless network connection, and enter the password when prompted.
You can use the step by step install wizards supplied with the router to do it all semie automated if your prefer.