On Starlite, we use the GriefDefender plugin to protect your builds. When you first join, you will have a Golden Shovel in your inventory. You can easily get another one by using /kit claim if you lose it. This is the item used to claim land. If you'd like to see who owns a land claim, simply right click the area with a stick.
To create a claim, right click two corners to create the boundaries of the claim, here's an example:
Each hour of playtime you earn more blocks to claim land with. You can also purchase more blocks using in-game money with /buyclaimblocks. One block costs 10$ in game money.
You can invite friends to your claims using /trust <username>. If you need any more help use /help in-game, then hover over "Land Claim Commands" for an entire list of claim-related commands.