Click the network icon of GNOME panel, select “VPN Connections -> Configure VPN”;

Go to the “VPN” tab and click “Add”;

Select “PPTP” type and “Next”;

You will be prompted to fill the “Gateway(server domain name)”, “user name”, “password” and “name(anything as you like)”, you may keep the “NT Domain” field as blank;

The most important, in some case, you need to click the “Advanced…” button, and select check box “Use Point-to-Point Encryption” then click “OK”.