When you first place down a Chest on the medieval-realm.net server, a 9x9 claim will be automatically setup around it protecting the area. Note that this only works the first time, and the chest cannot be within an existing claim.
You can use the /claim command to make a claim. Simply type /claim <size of claim> to create a claim. The size you input will be the number of blocks from you to the new border of the claim. You can just use a Golden Shovel to do it instead, right click on a block to set the first corner and right click on another block for the opposite corner, claims cannot be smaller than 25 blocks.
By default, nobody will be able to build or do anything on your claim. If you want to add someone to a claim, however, there's a set of tools you can use to do so giving various levels of access.
On the flip-side, you can remove a player from the trust list using the /untrust <player> command. Another handy command is /trustlist, which lets players with permission trust and the claim owner view a list of everyone with permissions on a claim.
Finally, the claim owner can add the public to the different permission levels. Replace the <player> on any of the trust commands with the word "public"/"all"/"everyone" to do so. Of course, you can also use /untrust public to remove the public from the different trust levels. Note that the public cannot have permission trust.
You can do /unclaim or /abandonclaim while standing in a claim to remove it. You will then be given back the claim blocks to use with other claims. In addition, you can use /abandonallclaims to abandon all of your claims and regain all of your claim blocks back for use. You can also abandon all of your claims by typing /abandonclaim or /unclaim while standing outside of a claim.
While holding a stick in your hand, you can right click within a claim to view the claim borders marked in temporary Gold Blocks and Glowstone. Any subclaims within the claim will also appear marked in temporary Iron Blocks and Wool.
You can also view a list of all of your claims and their co-ordinates using the /claimslist command.
Simply right click one of the golden corners of a claim to resize it. If you make the claim larger, you will need to have the right amount of claim blocks to support the expansion.
It's possible to enable explosions within a claim by standing in it and typing /claimexplosions.
By Subdividing Claims, you are able to create subclaims within a regular "top-level" claim you made. This is useful in particular for creating plots in a town, as you are able to trust people in a subclaim without them being trusted in the larger claim. Unlike regular claims, there's no size limitations on subclaims and so they can be as small as one block; subclaims do not take up claim blocks.
Apart from that, Subclaims act like regular claims. They are marked out by temporary Iron and Wool blocks. Do note though, that players trusted in the top level claim will retain their permissions inside any subclaims. Only the owner of the main top level claim can create subclaims within it.
To create subdivisions, you will first need to be standing within the claim you wish to subdivide and type /subdivideclaims.
To remove a subclaim, simply stand within one and type /unclaim or /abandonclaim to remove it. If you now wish to remove the main top level claim you can now simply type /AbandonTopLevelClaim to remove everything.
As mentioned before, players trusted in the top-level claim have the same permissions in any subclaims created within the claim. However, you can restrict subclaims to stop this and specify specific permissions for all players within subclaims. To do this, stand within the subclaim you wish to restrict and type /RestrictSubclaim. Note that only the claim owner can do this.