Hello, @Robin
I don’t recognise the software that you are using, however, I’ll try to help you as if you’re using Seamly2D (perhaps you have some items hidden in groups).
You need the armhole “scaffolding” as i1n the image from Adrich’s book - points 15, 16, 14, 22 & 31 besides point 32 which you have. Then you need to draw lines from 14 & 22, at 45° angles, for the length specified in the book, according to the size that you are drafting.
Once you have all of these points, then you may use one of the curve tools to draw the curves that need to touch on these points. You may use the tutorial in this topic.