Yes, but you say I play the notes I want to play and I don't need to play all my notes for every metronome click. Well, if the song has 100 notes and I don't need to play a note for every metronome click, then how many from 100 notes I need to play along the metronome click, that it calls an using metronome and I can quantize my song to the right gridlines.. ? If not all the 100, how many of them..? Are 10 notes OK..? Or with other words, using 10 clicks of metronome of the whole song are enough to get right gridlines..? If I don't play all the notes of the song along the metronome click, how large or small % of the notes I have to play along with a metronome click from the song? I mean, if I am not very well using metronome click and playing the note at the same time, I can escape from it with doing that much less if not required all the notes of the song to play along with a metronome click. The question is, what amount (play notes+using metronome click the same time) is enough that quantization works and that gb realizes I have used a metronome (to get the notes to the right gridlines).

Quantization is not AI -- it doesn't "realize" what you're trying to do, all it does is move notes to the nearest gridline, so for it to work you have to play the notes in time with the musical bar/beat grid. If you feel you need to quantize the entire performance, then everything has to played along with the click to make that possible. If you're not a musician/player and are not comfortable playing parts in in realtime, then perhaps it would be better for you to step-enter the notes in non-realtime. Quantization is for players who prefer to perform the parts in realtime, but there's no rule that says you have to do that.

So I can quantize only these notes, which I have had played along with the click, right? You write "if you feel you need to quantize the entire performance". How common is to quantize an entire performance in pop music?

Yes, that's right, you can quantize only notes which have been played along with the click. Whether or not to quantize is a musical decision, based on the style of music and the performance. Some musical styles (dance music, EDM) would call for fully-quantized parts, while some other musical genres (rock) might sound better (more musical) if the parts are NOT quantized. With pop music, it depends on what you (the artist/producer) prefer, and how well-played the parts are -- do they sound good/musical without quantizing, or do they need to be tightened up, or are they so off-time that even quantization doesn't help and they just really need to be re-played..