Secure your village and make a land claim.
Craft a Golden Shovel and hold it. You then see how much land you can claim. (100 blocks per in-game hour)
Right click on the first location, you will see a glowstone and a golden block marker (only visible to you and not mineable).
Left click on the second location. You get the message: "Claim created!" if it succeeded.
Not satisfied with your claim, or do you want to build somewhere else? Use: /AbandonClaim (or /AbandonAllClaims) Use /Trust to have friends built within the claim, and /UnTrust if they are no longer allowed to build. Click here for more commands