GameMaker: Studio™ is one of "easily game-making" software. This software can let you make games by using program languages (like HTML5 and etc), and targeting many platforms ( iOS, Android, Windows Phone and etc.) I recommend "Professional Version". if you work with "Professional Version", you will get good-quality services (Texture Management, Developer Services, Mobile Testing.. and etc) that aren't in "Free" and "Standard Version", and you will be available to get more products like HTML5, Linux, iOS, Android.
You can learn and start to make your games with demos, tutorials that YoYo Games gives you, and user's guides in Internet.
is it needed programming knowledges? no, Drag-on-Drop system helps you to make games without prev programming knowledges. Also, In programming of GameMaker, It is easy for everyone.