You can spy and teleport to a person by going to admin menu and pressing F8 or was it F7. I'm not sure. You can also type /find [Player name]
Edit:This is great for new players!
To clarify that, as an admin, if you use /spy [Playername] you can set your camera to focus on the named player.
You can then press F7 to summon your blockhead where the camera is. This let's you bring your character directly to a player, while checking where they are/what they are doing beforehand.
/find [playername] brings you straight to them, but without you being able to know where/what they're up to.
/fetch [playername] brings the player to you. These are pretty useful commands that all admins should know to help administrate a server.