So here are the following steps those you can follow to make an ad-hoc network in windows 8.
first of all you have to start command prompt with administrative privileges in windows 8. you can search for it in windows 8 start menu(Just type cmd in start screen and right click on it and click run as administrator ).
we are going to do this with the help of 'netsh'(Network Shell) it basically helps users to configure network devices. we are going to use this first of all we have to check if our network interface supports virtualization or Not. so to check this we have to run following command and should check the status of Hosted Network Support. if the status is Yes then you can continue otherwise you have to update your network adaptor drivers.
Just type this command to see result
netsh wlan show drivers
Now you have to configure ad-hoc network
netsh wlan set hostednetwork mode=allow ssid=<network name> key=<passkey>
just provide a ssid and a passkey to the network. once you are done now you have to start the mode to setup wireless adhoc network just type the following command.
netsh wlan start hostednetwork
if you get some error like "Hosted Network Couldn't Start" then you have to disable and then enable your network device. once you have enabled it you can share the Internet connection for the newly created ad-hoc network.
after following above steps you will be able to share your internet connection and create a Wi-Fi ad-hoc network easily if you got some problem just ask..