Windows Mobile 6, using PPTP
Go into Settings and select Connections.
Select Add new VPN server connection.
Enter a name (any name) and the server hostname (default: vpn.12vpn.com). Also select IPSec/L2TP.
Select A pre-shared key and enter the relevant pre-shared key. (Which you can find on 12vpn AFTER logging in and choosing the Servers page.)
Enter the username and password that were provided to you in your Account Activation e-mail and select Finish.