For most Linksys routers, you can open its configuration system at
http://192.168.1.1, no username, password "admin". Note that this is not a page on the net, this is being generated by the router itself. Different versions of the router may have different configuration menus, but one of them is port forwarding. You'll need to either find out what DHCP address the machine you wish to download is from and forward ports to it. In the case of two different computers using BitTorrent, you'll need to forward separate sets of ports to each machine and then configure each one's BitTorrent (in Prefs) to use that range.