You gain a set number of claim points based on the number of members in your company. Once you have enough points you can attempt to place a claim flag on an unclaimed island. This costs increasing amounts of gold based on the point total of the island. Whoever places the flag needs that gold in their inventory. You cannot claim lawless or freeports. This places the flag and then you have to wait an hour for the process to countdown. If someone decides to contest your claim on pve they need to drop a flag in the radius of control of your flag while claiming. This halts the timers on both flags. If you pull up your flag and move it, it costs the initial gold amount again. On pve this mostly does not happen except in the case of popular islands that may have people watching and waiting for the current owners to go into default. At the end of that hour you get a message and the island is yours. You need to place the initial claim amount of gold into the flag every 12 hours to keep maintenance on the flag. If you don't, you lose the claim and the process starts all over again. If the cost to claim was 50g, then you will need 100g every day to maintain that flag. Only people in your company can add/remove stuff from the flag, and you can admin lock the contents if needed.
You, as the owner then can set the tax rate and message for the island. The current cap is 20%. This is an additive amount in the case of resources. Nothing is taken from the harvester. Those that do treasure maps on your island do however have gold taken from their total. You can destroy any NEW structure placed within 24 hours. You receive a message when someone "settles" on your island. If they place a foundation you receive a message, but other actions trigger that message too. You cannot remove structures that have been there longer than 24 hours, then the normal 10 day decay timers apply.