There are 2 ways to do it
1/ Connect the WiFi unit via USB and check which lamps are active, if it is not connected via your home network the end 2 lamps should be lit one is for power the other indicates the unit is in DtoD Adhoc mode. Use the WiFi utility on the PC to connect to the GS911 and you should be able to get to the web interface by entering 10.0.0.1 into the address field of a web browser. (I am assuming here the PC has inbuilt WiFi, you could also use your smart phone or tablet to do it)
2/ Connect the WiFi via USB and launch the WiFi Utility, there device should show up in the utility and you can enter your home WiFi details, the GS911 will then attempt to connect to the home network and you should be able to launch a web browser to access GS911 via the button in the WiFi Utility
One other aspect is I would be tempted to restart the PC, connect the GS911 WiFi and confirm Windows sees it in device manager. I would also turn off any USB power saving click boxes. WIn8/8.1 is known to be too aggressive in power saving modes. Once you get into the GS911 Web Interface there is also a power saving setting in there I normally turn off as well