Entities cannot be hot-deployed, so we need to stop the server.
Create an Entity using the New Entity wizard File > New > Seam Entity.
You should select a necessary project, type a name for Entity class, select a Package using Browse button, type a name for Master Page and Page.
The Master Page and the Entity were created in WebContent folder.
The Entity page is:
Run the Entity page on server. This is what you get: