If you take the code to http://www.womrealms.com/ and put it in the box at the bottom of the page, this will make you a World of Minecraft:Realms account.

Now if you go back to the World of Minecraft:Realms server and type /home, you will go to your own "Realm" where you can control who can and cannot build.

Good luck

also, on the womrealms.com:
1) you can change the size of your realms after you rank up
2) you can change the permission to build that different people have in your realms
3) you can access the rep store where you can buy a clan application or start a new clan
4) you can access the clan manager page if you are part of a clan