How to unlock my iphone 4 on computer?

I have seen a lot of youtube video about unlocking iphones without computer.
but i don't have Wi-Fi in my area and my iphone says 'invalid sim'
so only way to unlock my iphone is using laptop!

Invalid sim message display if your phone locked to network… Currently it's on network lock… You need to unlock it. You need to connect I-phone 4 to computer or Laptop to Unlock it… You can use Remote Unlock service to Unlock it. You need internet connection to get Unlock service through mail. But Wi-Fi not needed in this method. If you don't have internet connection, please move to your friends or some place where connection available and unlock it there… You can get the Remote Unlock service for I-Phone 4 at http://www.theunlockarena.com/apple-iphone-4/rs13wp9/ and Unlock it easily. You need to specify the network, country it locked now and get the remote unlock service here Unlock it easily.

This helped nothing I want to use a computer however there's no answer or reply for it