What is the Operating system on the laptop ?
If it is XP then in the bottom right hand corner you will find Wireless network connection ( looks like 1 computer monitor). Use that icon to connect to the wireless network.
If it is windows Vista, then in the bottom right hand corner you will find 2 computer monitor icon. Use that icon to connect to the wireless network.
If it is Windows 98/ME/2000 then use the adapter utility to connect to the wireless network.
For MAC you will see the AIRPORT icon at the top.
Check the wireless settings of the router first . Make sure that yopu have all the wireless settings of the router. If you are not sure about the settings, then open the router set up and check the settings.
Click Here for step by step instructions on how to connect to the wireless network and troubleshooting steps