Connecting to the internet on my laptop

Question

Well i'm trying to add my laptop to one of three internet computer connections on my Belkin Wireless G Plus MIM0 etc.(The other connection is being used by my main computer). But i've tried everything to add it, but it's just not working, i have also bought a Belkin internet Modem Cable to plug into the back of the laptop and the Router, but that hasnt worked either. The disc which came when i bought the Belkin Wireless only contains a manual and other usless information.