You didn't mention the devices b/w whom you want to configure site-to-site VPN.

I hope u are using PIX/ASA.

hope this helps:-

http://www.cisco.com/en/US/docs/security/asa/asa80/configuration/guide/site2sit.html

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a00805e8c80.shtml

and on ASA 8.x there is a hidden command which can show you what steps to follow to complete the setup

ASA-5510-8x(config)# vpnsetup ?

Configure mode  commands/options:

  IPSec-remote-access Display IPSec  Remote Access Configuration Commands

  L2tp-remote-access   Display  L2TP/IPSec Configuration Commands

  Site-to-site         Display IPSec  Site-to-Site Configuration Commands

  Ssl-remote-access    Display SSL  Remote Access Configuration Commands