Import Contact from other sites

HI
Can any one help me with this. I am trying to make a system in my website from where people who are already member in my site can invite contacts from their gmail or yahoo or from other sites account. They will login into those sites then they can directly see all his or her contacts. I want to make it in PHP.

I got one solution for these from openinviter dot com. But when I am trying to install it it is giving me error that wget is not installed. I have installed wget and changed the config.php file. Then also it is not working. Please help somebody.