How to make an entity

I want to create an entity which is look like a giftbox. I mean a giftbox on the lobby in NetherGames or CubeCraft. Can anyone help me please

 

Yes, can someone could define how to create entity, spawn it move it and more .... ?

 

They're most likely using player entity with a custom skin geometry, which means you'll need to create your own model and apply it to the fake player entity

 

I have model already. But I don't know how to create fake player!

 

Take a look at how slapper does it.
https://github.com/jojoe77777/Slapper/blob/master/src/slapper/Main.php#L130
https://github.com/jojoe77777/Slapper/blob/master/src/slapper/entities/SlapperHuman.php