Connecting my laptop wirelessly to internet

Sir,
I have a desktop computer that is hook to a SMC wireless ADSL2 Barricade 54mbps broadband router and I have no problem accessing into the internet with it. I have now an Asus notebook model A3500E with Pentium M processor 740 Centrino. Using this notebook in another room, I tried to wirelessly connect to the internet through my router but without success, Please advise what I need to do. Thanks.

Michael