No browsing issue on PPTP VPN Server on CentOS 6 64bit

I am trying to setup a VPN server in CentOS6 64bit. I used the first 4 steps of following document to setup the server . http://ift.tt/UvmhYm

And i successfully managed to setup the VPN. And i also managed to connect to the VPN from MacOS X. But the issue, is i can not browse anything. I can not ping to any site, except for i can only ping my VPN's Server IP. Other than that, which ever IP or site i ping, there is a 100% Packet loss.

I am sure something is wrong in my settings in my VPS, but not sure what it is. Any idea?

Edit: I am on an openVZ container, and tun/tap is enabled.