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Depending on those services, you need to construct an access control list (ACL) to allow that inbound traffic. You'll also need to statically translate the DMZ server to a public IP address that the world can route their traffic to.
Based on your diagram, it looks like you'll be double NATing (two NAT layers), so there is a little bit of added complexity. You may want to consider putting your DSL router into "bridge mode" meaning it won't have an IP address on, it will just pass traffic from the phone line to the Ethernet interface and back...it would become a media transceiver of sorts (phone line to Ethernet media conversion) and it would not actually perform any routing or translation functions.
If you don't want to do that, then you can leave it like it is, only you'll need to allow the inbound traffic through the DSL router.
I think you need to provide more info on what you want to be able to do with your network setup and we can go from there. You've already outlined what your network looks like, but what services do you want to allow? What do you want to do with this network?