I went to multiplayer and pressed “New Server” I entered the name I want it to be and the address. I pressed done but it said “hostname not available”
“New Server” doesn’t create a server; it just lets you add one to the list of servers you connect to regularly.
To create a server, you have to run the server executable, “Minecraft_Server.exe” or “minecraft_server.jar”. Detailed instructions can be found on the minecraft wiki if you need more help getting set up or run into performance issues. If you are running the server on the same machine as the client, you can connect to “localhost” as the server address, or your own IP address.