Urgent Network Help!

Hello,
The names Hayden.
Recently i had reinstall windows on my old windows xp home edition desktop, so I have been having a bit of network trouble. Previously and currently I am connected to a Belkin router (N+) I think and some sort of Webstar modem (If this makes any bit of a diffrence). More over the problem I have been having is connecting to the internet or the network of my home via my computer although I am currently able to access the internet through my brothers computer using the same modem. I have looked through countless amount of videos and forums about how to add my computer to the network, let alone the internet but nothing is helping. I am trying to do this all through ethernet because that is how the internet was working prior to the re installation of windows xp on my computer. You can say I'm a beginner at this computer stuff. NEED HELP CONNECTING TO NETWORK!
Thanks