Scoreboard Player First Join
I want to make a scoreboard on my server that broadcasts a message to players who join the server for the first time, but I don't know what the scoreboard is. If you don't know what I'm talking about here's an example /scoreboard objectives add join [MY PROBLEM]
Here is an explanation on how to make something run once
basically what you want to do for the first time they join the server is
/tellraw @a[tag=!join] <your message here>
/scoreboard players tag @a[tag=!join] add join
in a repeating-chain.