how to add user and password authentification to Openvpn

[call]

I've done a Road to Warrior VPN in with TLS auth under Debian Whezzy

I just want to introduce a user and password authentification because if someane steal my computer can have easily acces to my net.

I've tried many things but I didn't succed. There is hardly post in the internet that explain how to do that.

I've tried using LDAP, PAM... But no succed at all. If I apply the configuration then the server doesn't restart

Is there anyone that can send me a link or explain me in details how to do that?

Thanks