how to build a level editor

hello all (i can not speak english well sorry for this )
i want to create a level editor for my game engine but a can not … How do I correct tool (qt , gtk , mfc ,… )
How to fix a screen that The show stage game
thank you

Surely the only person who can answer your question is you!
Only you know what is required for a level editor for your own game! I suspect you’d use the same tools for the editor that you used for the game.