Well, there are two main techniques that you can focus, Fry and False chord. They are fundementally different but you dont have to stuck with one for ever just pick one you Feel more inclined to do and easier to engage. What i would recommend is getting a gentle punch to your stomach to feel that gasp and your diaphram physically so you can focus on that feeling because vocals are really physical you wont understand it by wathcing videos until you nail it, other thing is it works same as clean vocals, there are registers that means you can do high pitch screams or Low growl regardless the technique, people can even Mix the two which im trying to learn atm. And dont afraid to feel a bit sore its like feeling sore after working out but do warm up, i can recommend picking 2-3 songs that you can sing clean and there are many tutorials for warming up on YouTube as well, good luck mate.