I have a router with one usb and one ethernet port can I still make a network with two computers and a shared internet connection?

I would imagine that the USB port is for a device such as a printer or an external hard drive. If the router is not wireless and has only one ethernet port then only one computer can be connected to it which doesn't make much sense. What is the make and model of that router?

Actually I can connect the PC through the usb and use the net... us robotics usr9112

Ah, I see, that's your ADSL modem. It looks like this I assume. Then yes, if you currently have your computer on the USB connection then you can add a second computer on the ethernet port.