Do you mean showing different pages based on the users IP/ Country? If so you need to get hold of an IP to Country database and then on a new session get the users IP, look it up in the country from the db and then handle the pages as appropriate (redirect to the relevant country folder/ set the culture etc). Be aware that these arent fool proof methods particularly for people using computers in large corporations or using proxies as their gateway to the net may well be in a different country to themselves.
There are a couple of good ones http://www.ip2location.com/ and http://www.maxmind.com/app/geoip_country I prefer the one from maxmind personally but they are both good.