You can obtain a golden shovel by crafting one or by voting four times.
You start with 500 claim blocks. You can gain more by voting or purchasing them with /buyclaimblocks.
Creating a Claim
Hold the golden shovel in your hand. Right click one corner of the area that you want to claim. Then, travel to the opposite corner of the claim.
Right click the opposite corner of the claim
A claim should generate as soon as you right click the opposite corner. A proper claim will be marked by glowstone and gold. If the claim is not marked by glowstone and gold, a reason for its failure will appear in chat.
To list your claims and view your claim blocks, type /claimslist.
To remove a claim, stand in the claim and type /abandonclaim.
There are four tiers of permissions for claims. The higher tiers inherit all of the permissions of the lower tiers:
/accesstrust [name] allows the player to interact with redstone devices and kill hostile mobs.
/containertrust [name] allows the player to interact with chests and other containers. The player will also be able to interact with and kill friendly mobs.
/trust [name] allows the player to break and place blocks in the claim.
/permissiontrust [name] alows the player to trust other players in that claim.
To remove a player's permissions from your claim, type /untrust [name].
You can replace [name] with all to give all players permissions in your claim.