I am new to visual design and have already read dozens of articles about color, typography and other related things. But I can't understand how to use the elements and principles to create a professional and amazing looking layout. As I can't find anything useful which throws a light behind that layout. So, can you give some insight to it? It will be of huge help.
If you see a pleasing layout you probably can find "this and that rules seem to be applied". As well an unpleasant layout can be explained with some rules ignored.
As you already have found, all rules are declarative, they aren't construction receipes. It's the same as the law. It tells what you should avoid to stay in front of the bars. There's no receipe for pleasant living. You must build the receipe by yourself as habits, knowledge, skills and communication.
In graphics a creative designer can break some common rules if he has something for balance. What it should be? Only its inventor knows, no rule exists for it.
When people watch a design they have some on culture-, education-, brain capacity- and personal experience dependent way to decide is this pleasant, neutral or unpleasant.
You have it, too. Find some pleasant designs. Try to copy them as is to develop your technical toolbox to be up to the task. Start with something simple enough for your skills, maybe as black and white only in the beginning. Be sure that developing graphic software user skills takes time months...years depending on how ambitious and talented you are.
Remember: Software is a tool only. Pen and paper sketches are extremely useful because one cannot waste his time by playing with tricks.
Try to compose the things properly for other page dimensions. You will see, if you succeed or fail.
Then try to change the content. Use the same design for example to advertise or claim something else. Try to find which content is dissonant with that design and which kind of content fits.
Next try to find totally different design - if possible, your own design for the given content (which is proven to be possible to have a good design)
When you have repeated this few hundred times you maybe have developed also own ideas. If you in some phase happen to be able present something of your totally own (=the idea of the content, actual content and its graphical presentation) you are an artist. It can take years and many of us still haven't anything interesting enough to say after that time. But many more of us at least have developed a capacity to make good designs on demand with defined goals.