Wireless internet with Dlink problems? Main computer connected to internet w/ USB...

[saiyan_girl]

I just bought a dlink router (DIR-635), and I can't connected.

Im staying with a family for 6 months and they gave me laptop to use. However, their office is too small and its awkward havin a computer and my laptop here... anyway
I bought the Dlink (these people here arent too good with computer things) and now I just noticed that the main computer is connected to the internet through a USB cable.
However, my laptop is connected through an ethernet cable.

The instalation wizard asks me to plug-in the ethernet cable in the router then another cable going from there to the computer. So when I use the one from the laptop, and connect it to the main computer, it doesnt work. While checking physical conectivity status it gives the following error:
"Problem found on connection to the gateway, do you want to change your IP settings to DHCP Client`? DCC requires this function to continue"

Pressing okay doesnt do anything, the same error pops up again

I thought that if I connect the ethernet cable from the modem to the main computer (instead of my laptop), the internet would still work. However, that's not the case apparently....

I think that what would fix the problem would be if the main computer would be connected to the internet through an ethernet cable from the modem, not an USB cable... but I dont know how to do that...

anyone know?
Or does anyone know how to make it to work with the USB... (i dont know... Im not that good with computers)

I hope I explained the problem well enough, and thanks in advance for the help. Any advice is greatly appreciated...