When you create a world, you have the option to open the world to the public. You can do this from the pause menu by clicking the Open World to Public button. Once you do this, your world will be posted to the multiplayer section of the game, along with your name and world title!
There are 2 commands in MineKhan: /ban and /online.
/online - shows you what people are online your server. If you have not opened your world, it will say: You're all alone, sorry.
/ban <username> - Bans someone from your server. You might use this in the event that the user is griefing your builds, or is being toxic in chat. For this to work you need to be the world host. When banning someone, type their full username. If it is difficult for you, you can use /online to see it. If you are not the world host, it will say: You don't have permission to do this. Once you successfully ban someone, it will appear as they left, but in reality they have been banned and cannot rejoin the world unless you open it again.
It is possible to get permanently banned when using MineKhan. This happens when you attempt to login 20 times in under one minute, such as repeatedly clicking Login with an incorrect password. When you do get permanently banned, you will see a message pop up saying "banned forever lol". This means you cannot access anything on his site, including MineKhan.