your server on your local machine should be set as an internet server. you will also need to forward your ports. a better way to do this would be to run a server and get it hosted professionally as your machine will struggle to both run the server, and the client portion.
Moving to Server Discussion. Check out this thread as well. How to do a Quick Map Test - Local Server Best bet is as pepper said though, get it hosted. It will allow all your players to play lag free =) *** Check the blue banner on the pages for a deal with tf2maps and gameservers.com!***
