Can someone please tell me how this would be set up, We have a third party company do it for us so I dont know how they did it. Basically we have a large cisco router at our head office, all the dsl routers about 200, all come into this one router. They are all assigned a 172.19.x.x address range i.e 172.19.54.x etc etc. How would the cisco router this end be set up ?
It really depends on the solution that your ISP provides.
If your ISP is providing an MPLS network between main and remote offices then the router configuration can be really simple like default route or some static routes or simple BGP configuration. In this case most routing decisions are made on the ISP PE routers within the MPLS network. In short, MPLS network is normally an ISP network which provides routing and QOS between client sites by the use of "packet labels/tags".
If your ISP only provides the internet connections then you may need to configure GRE/IPSEC VPN tunnels on your routers which may be a little bit complex.
But actually do you need to configure the routers or your ISP also provides the configuration and implementation?