A lot of different things can be learnt from you tube, however freediving is an activity which carries many real dangers, you can literally die if you don't understand the dangers and the principles behind it. In my opinion you would be better off using this forum to do your research along with other platforms and ideally find someone who knows what they're doing to teach you. Whatever you do, don't just grab a pair of fins and try to go as deep as you can, you may feel really good one minute and then you can be dead the next. Freediving is the old saying, fools rush in where angels fear to tread. Take it slowly, really slowly and never be tempted to bring ego into it, that ends in tears. Good luck and look at everything on this forum,