How do I make the player list appear on a block?

I'm trying to get the player list to be on a block and constantly update as players leave and join but I cant figure out how and I believe I have seen it done before in other games. I have tried using a leader board script to try and do it but I don't think that's how and I can't find a way to do it anywhere. I don't know if this complies to the guidelines or rules but I would appreciate the help. Thanks in advance.