Detailed information can be found at (whithin these URLs, there are several links to undesrtand and configure MPLS/VPN with ISIS or BGP):
MPLS http://www.cisco.com/warp/customer/105/mpls_index.shtml
ISIS
http://www.cisco.com/warp/customer/97/index.shtml
BGP
http://www.cisco.com/warp/customer/459/18.html