In order to connect your device to your computer, you need a compatible USB cable. Plug in the cable to your PC USB port and wait Windows to recognize the device. After that, download and install Nokia PC Suite and launch it. Navigate to Tools > Software updates, select the latest file and click Install.
If your computer doesn't recognize the phone, press Windows + R key combination, type devmgmt.msc and click OK. Expand the Universal Serial Bus controllers list, right-click on the driver and select Uninstall. After that, reboot your PC, connect the device using the cable and press Scan for hardware changes icon from Device Manager. Windows should automatically find and install the driver.
Also, you can try updating the firmware from Menu > Settings > Phone > Device update, but for this you will need to connect your phone to a WiFi network. Check the official web page for further information.