I would recommend starting with the LightBurn documentation itself, it is extremely well written and with its instructions also a good starting point for installing one’s machine correctly.
Then, and, or in parallel, I will watch the many fine videos on youtube, starting with LightBurn`s own series of simple and basic tasks.
But, you also need to consider whether it is the right toy for you or not. If you do not like to learn, are not computer minded or just do not have the time needed, then you should drop it.
I compare it to the advanced knitting and sewing machines available today, I am fascinated by what they can be used for and how they work, but I do not have the time and desire to get serious about this topic. So I buy my sweaters 
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