Communicating through the internet is hard and it is likely to misunderstand others if you are a newcomer to a topic.
The best way to get the ropes as a beginner is to ask someone else on the course for advice who can already throw decently. When you are new there are likely popping lots of fundamental problems up about the backhand as it is a complex move only few know from other sports. Maybe that is also why many beginners will develop good forehands at first, because the forehand is like throwing a ball/hitting a ball with a stick. Getting new players to turn back all the way and sling their arm forward is really difficult and might also feel really awkward for the player at first (try throwing a backhand with your offhand and you will see how unnatural throwing can feel) and it will take a lot of repetitions to get a good feel for it. A player on the course can correct your form on the fly and I think many are happy to help a new player out.
Coaching through videos or forums requires a good understanding of the throw (imo) in order to know what people are even talking about. Most of this content is aimed at players familiar with throwing already and playing a couple of years so keep that in mind.
Depending on your goals and whether it is fun for you, I cannot recommend enough reading through all the endlessly long form discussion threads on this forum. It often requires some abstract thinking (for example when golf guys are posted) and often wont make too much sense until you experience some of the concepts discussed. I can accept that a weight shift generates more power, but until I experienced it generating power that was only a truth that existed in theory for me. The various youtube coaches talk about form in less abstraction and that might help you to understand some concepts a little better. However, I never gained much from watching tons of youtube form videos and trying to apply them. It helped me understand how to throw, but not what I did wrong.
Videoing yourself is the best advice I got. Whenever I see myself on video I look on in horror by discovering what I thought I was doing and what is actually going on. Posting my videos in this forum has forced me to work through some form changes I would never have seen myself or have thought of tackling (thanks to sidewinder22 and Brychanus for making me take on these changes). I often dont see through the uses of drills or concepts, even weeks after doing them. But sometimes I find the missing link to apply them to the throw. Learning through this way is like throwing stuff at a wall and see what sticks over and over. But more things tend to stick over time. It is interesting to click through some of the form threads and follow the form progress of the people posting over there. The people giving advice really work some magic on people and you will see beginners get into really good positions over time.
Form progress is very fickle and progresses best when you work on a single thing at a time. Dont let impatience impede your progress but try and train your body to do the one thing you want to change to stick and become automatic. For me a change will at first result in a lot of shanks as everything is off and about 5 weeks in it becomes more automatic. Give yourself time when you learn something new, see it through and congratulate yourself on every change you make. And dont compare your progress to others, it is of no use.
Lastly, stay loose. This advice has also made no sense to me until this year. When it makes sense to you, you have made great progress.
I concur! Making great progress, and my process for that is: watch/study videos to learn what throwing correctly looks like, get video of my throws, break it down frame by frame, find what I am doing wrong, and fix it.
Update: So far I fixed rounding, I use an x-step and I fixed starting my throw before planting, widened/staggered my final step stance (which fixed my hips turning too soon, and not transferring any power to my throw), and am now working on a longer reach back, making sure I start my throw with my hips, and allow my arm to be loose, be dragged into the power pocket by my body, and fire fast late in my throw. The new staggered stance is messing a little with my aim, but overall, the changes have resulted in amazing progress! I went from max distance of 200', to 225', to 245', and now a rare throw out to 265', maybe even 275'. I have also become a lot more consistent! I played 4 rounds today at the beginner friendly local course, 9 holes, and I shot 1 over par, par, 2 over par, and 1 under par! The par tied my best ever, and the 1 under par is a new personal best. On 2-3 holes I had new personal distance best tee shots, with some breaking other recent personal distance bests! I have said all along the DG journey to improvement is two steps forward, one back, and it has been, but right now I am definitely making two steps forward! I appreciate all of the feedback, help, and encouragement I have got here! Also, spent months playing mostly throw two discs, play from the best one, but these are scores from regular DG - one throw at a time, every throw counts! I still love the two disc, throw from best disc rounds as a great tool - I get more throws, more practice for less overall walking, fix things I do wrong on the first throw, and gain confidence from the lower overall scores.