What Is Looping, How to declare it , which one do you like most

Lottery Game play

Hello Folks;On the picture is my front-end then this is my loop code, and the action code but each time i thick on the respective box am expected to get the value number of the boxes i checked but i keep getting this error Warning: Undefined array key "thick" in C:\Users\pc\Backend_class01\play_game.php on line 12please i need to know where am not doing it right being that the...