When you playing Guitar (a Melody) you hit all the strings? I hit all the strings (Strumming) but it makes no good sound ...,Should I hit or strum all strings or some of them during playing a melody?
Strumming plays chords, up to 6 notes that sound harmonious together. Usually it provides the rhythm and accompaniment, not the melody. You have to use your left hand fingers on several strings at once. Most beginner guitar books/methods show you how to play basic chords.
Beginning melody playing is the opposite. You press one string with the left hand, and pluck just that string with the right.
With experience you can play several strings at once or in rapid succession. But for the beginner it's all for chords, one for melody.