From MineRealm Wiki
The MineRealm realms system is a unique aspect of the Survival server, enabling users to claim land. The entire survival map is divided into 40,000 (50 x 50) realms. Within a realm, the realm owner can grant building privileges to other users. The system also does not force players on the server to be individualized.
Here are some commands used for realms.
/realm - Shows you info about the realm you're in.
/realm users - Displays users with building privileges.
/realm purchase - Purchases the realm you're situated in.
/realm motd <message> - Sets the Message Of The Day for the realm.
/realm name <name> - Sets the name for the realm you're in.
/realm add <user> - Grants the users building privileges.
/realm remove <user> - Revokes the users building privileges.
/realm sell - Sells the realm you're situated in.
/realm sell <user> <price> - Sells the realm you're situated in to a user.
How do I create a realm?
It is not possible to "create" a realm, as all realms are already defined on the map. You can, however, purchase a realm. To see info about the realm you're presently in, type "/realm" at any time.
How do I purchase a realm?
Realms can be purchased by typing "/realm purchase" when standing within a realm. You can't purchase realms already owned by another player. To purchase a realm, you must pay 10,000 realm credits.
The realms surrounding spawn were sold for 50,000 realm credits each.
Can I sell my realm?
Yes. Simply type "/realm sell" within the realm. Selling your realm will give you back what you paid for it, minus a 10% fee. Optionally, you can sell your realm to another player, and specify your own selling price. To do this, type "/realm sell <user> <price>".
What do realms do?
Realms protect all blocks you place within the realm, so other users can't remove them. Additionally, other users can't place blocks within your realm. Also, any chests that you place within your realm can't be accessed by other users. Realms also give you the ability to set a MOTD for the realm, which will be shown when a user enters the realm.
Can I have more than one realm?
Yes. There are no restrictions regarding the number of realms you can own.
Can I let other players build within my realm?
Yes - to give a user building privileges within your realm, simply type "/realm member <user>" within the realm. Optionally, if you wish to remove building privileges that you've granted for a user, type "/realm member <user>". To view users that you've granted building privileges, type "/realm users".
How do I set the realm MOTD?
To set a MOTD for a realm, simply type "/realm motd <message>". This message will be displayed whenever a user enters a realm. You can set the MOTD for realms you own.
Is there a way to group chat with users building in my realm?
It's recommended you use the Guilds System, which enables you to group chat with a set of specified users. Information regarding how to use the guild system can be found in-game, by typing "/help guild".