DS Lite Wi-Fi?

Sorry about all of these help Threads, but I really can’t figure this out. My little bro got a DS Lite and now is constantly bitching to me that I need to get the Wi-Fi working. I’ve gone on the nintendo W-Fi site and all, but I can’t seem to access the DS’ Mac address. I need it because our Broadband can only be accessed by the equipment that is authorized via Mac address. I’m not sure if we need one of those Wi-Fi cards for the PC/router either. His DS also keeps picking up some signal from another area. I’m pretty sure it isn’t ours because it kept going on and off, but I was still using the internet. If anyone can help me through this process I’ll be very greatful.