There are no main server on terraria so I would suggest google searching "terraria servers" and see what comes up. I have done this and been on multiplayer.
Just Google Terraria servers and copy the ip address into the multiplayer slot on terraria.
Unknown
you cant you have to connect to the enternet if you have access
if you created it right then they have to know you multiplayer server address to get to your multiplayer server
Type in the IP address or Hamachi address of your friend's correctly or play the premium Minecraft. Myncraft1: Your friends has to be on (Hamachi) to connect to his server
The server version should be in the title bar. The client version is in the bottom left corner of the main menu. If they're not the same then it won't work.
Is the server up? or is the owner asleep or somewere.
Type "What is my IP" On google and copy/paste it in your direct connect box if you have your router port forwarded and a server program running on your PC
Maybe it's your internet?
Low memory space...?
They might be hamachi run.