How can I set up sub-domains in Nginx? Things I have set-up already" Nginx running a Ruby rack app DNS set-up with DigitalOcean How do I create a sub-domain to root to another ruby app?

I'm trying to reinstall nginx but the config files have been deleted and I dont know how to reinstall the default ones.

Are there any good link/resources deploying a Rack app(Not rails!). So far I have the Rack app set-up with the folders and such but I have been having LOTS of trouble with the nginx part so I uninstalled and decided t...