Hi Rabnawaz,
The best advice is configure a site to site IPSec vpn tunnels between sites (may be hub and spoke).
If you know that there will be not much traffic between spoke sites then this is a good idea.
If you know that there will be a much traffic between spoke sites then, I would suggest go for DMVPN where spoke and spoke can communicate without coming to hub.
The things required to configure a IPSec vpn are, Interent connection at each site with static public IP. And you need k9 bundle of IOS version running on the routers.
Please see the below links for more related information and configuration examples.
http://www.routergeek.net/general/how-to-configure-site-to-site-vpn-in-cisco-routers/
Hope the above clear and understand you.
Please rate all the helpfull posts.
Regards,
Naidu.