If you need to get some information on where the person is located you need to get the IP adress. When you have it you just enter it and IP2Location will in a few seconds provide you with data! If the person is on a mobile phone, its quite obvious that it will no detailed information as it will show the provider.
There is many ways to get hold of an IP. You can get the person to send you an email, and view the code behind the head. This can also sometimes be hidden or if its in a VPN, you will getting a different country! BUT, this tool has a large DB and I cant wait to be able to explore everything! :)