I'm all new to the guitar and started taking these on line classes

i seem to be having an issue with my left hand as to how to hold the neck and use my fingers on the strings

I can't seem to hold down a string without hitting the adjacent string and muffing it. Is it just going to take practice and time ?

I don't want to get discouraged I really want to make this work my wrist is killing me I must be doing something wrong

I just don't seem to be able to make out from the video as to what to do to correct this. Any help would be much appreciated.