I'm trying to get an item to spawn when the player first enters the world however trying to find out hasn't proved easy, so i thought i'd just ask, how do i do this?

One way would be:

 

1. Register a class instance with the Forge Event Bus (in server proxy)

MinecraftForge.EVENT_BUS.register(MyClassWithSubscribedMethods.instance);

2. Subscribe to the EntityJoinWorldEvent in that class

3. Check if the entity is an instance of EntityPlayer

4. If it is, then read/write a value to the entity data to check/mark when they have FIRST joined the server

5. use World.spawnEntityInWorld to spawn the item or World.setBlockState to spawn the block.

 

I'm relatively new to modding, but this is how I would tackle the problem at this point.