its not working for me in my files i font even know where to find the application
Instructions how to use the engine are on https://castle-engine.io/ , in particular see the "getting started" page ( https://castle-engine.io/documentation.php ) and the manual ( https://castle-engine.io/manual_intro.php ).
There is no visual application distributed with Castle Game Engine. You usually install Lazarus ( https://www.lazarus-ide.org/ ) to have an environment to edit and compile Castle Game Engine games.
If you expected a visual editor included inside the engine, like Unity3d editor --- I'm sorry, we don't have it yet. But we are working in it, see our plans for 2018 https://castle-engine.io/wp/2017/12/23/plans-6-4-release-asap-visual-editor-soon... :)
Note to whoever reads this: the above comment is outdated. The current engine (from this itch.io page, or from https://castle-engine.io/) features a cool visual editor to design your games visually. See https://castle-engine.io/manual_editor.php .