|There are two steps to get an island on the world map, for others to visit:|
1. Finish the sandbox. When this is done, your island will become 'promoted'. It will have full rights, just like a normal, public island.
2. When the island is promoted, you need to create a complete island, with more complex quests, more NPCs and other features. The requirements for getting an island public might seem high, but this is to give the game an overall better quality and appearance. A half finished public island with many spelling errors and bad links will give a bad impression to new players trying the game. A good storyline for the island is also a smart thing to implement.
Read the wiki info on island sandboxes here:Quest_for_the_Sandbox.