The black buttons, with white text are togglable when the player isn't joining. For the purposes of this, kitty cat, is the player. Change if the player is premium or cracked via the button on the top right. Change if they log on with the correct password in the top left. Once you have edited the settings. Press "JOIN" in the bottom corner to join the server with the settings specified.
acecheesecr14's 5 minute QUICK and EXTREMELY SIMPLIFIED version of what will happen. It gets a bit more confusing when you take into account what happens if the Minecraft servers are down etc. Love ace. P.S. Forgive me, I done this in about 15 minutes so you could get an understanding.