when i start a halo game on multiplayer people cant join i dont know why AND i stated a dedicated server and I couldent join and i made the game but i couldent join so if you can help me PLZ tell me

Mostly all multiplayer games and server software require you to set up port forwarding in order to host a game server if you have high speed Internet. When someone clicks on your game, they are connected to your router first. The router must be set up to transfer the connections on the ports server programs use to your computers' ip address. When I created a halo server, I first had to set up my router to fowared port 2302 (the default port for halo 1 pc) or whatever port you have set to use. For a step by step guide on how set up port fowarding, see http://portforward.com/english/rout...
This also applies to any server software, including web, ftp, telnet, etc. servers.