I think I must be doing something wrong and wonder if someone could point out or suggest what it maybe

basically, I am trying to simply fret but am having difficulty getting my fingers in the right place it all comes down to the 6th string I either catch the A below or don’t get

close enough to the fret to get the note

when it comes to the very first fret on the 6

this seems to throw me and I end up somehow with my arm at unusual angle

my thumb is straight behind the neck but I cannot seem to either hold this posostion and have to stop

I have followed the beginner videos but I am not getting it and my shoulder aches. My arm and fingers are fine. The question is what I doing wrong I am not gripping the neck but neither are the tips of my fingers on the string they are more at an angle and it’s impossble for me to reach and place my ring finger on the 6th 3rd fret holding my thumb in the middle. My finger just won’t reach and cover 1-3 with my thumb in the same position I have to move my thumb

So in all it seems my technique is all wrong. How/ can I fix this- the beginner lesson looks great holding your thumb and fingers seem to cover the frets. Alas not in my case

and it seems I have already hit my first hurdle before I even get started