firstly check that your web server is accessable by visiting...
http://10.0.0.12/
if you're trying to setup a service that's accessable by everyone in the outside world, here's what you got to do...
on the dsl router: set up a service to forward port 80 to 10.0.0.12
install a dyndns client on your computer and set it up to find the ip address via web(the router may even support dyndns, i know my netgear does)
depending on your router you may not be able to test your web server from inside by visiting
http://xxx.dyndns.org/ you may only be able to use it from
http://10.0.0.12/
you'd have to go to somewhere outside the firewall or use some anonymous proxy outside to test your
http://xxx.dyndns.org/ web service.