Just learn the minor and major scales (which are the same btw, one is a Greek mode of the other, also learn Greek modes) and harmonic minor scale (this one is not so commonly used but is very cool nevertheless) AS YOU learn songs and play around with them. Practice and theory must go hand in hand, don't focus just on one of them. With time you'll naturally develop a sense of what sounds good and what doesn't.
Also always keep in mind scales are just guidelines. Most songs use all 12 notes because they change key, use chromatism, modal borrowing, etc. Not to mention how intentionally throwing up something out of key can be a thing sometimes as well.
Also download Guitar Pro, it helped me a lot when I was a beginner and still does.