the first line is the bust point. (From shoulder to bust 8inches)
the second line is the under bust point. (From shoulder to below bust)
the last line is the waist point.
mark out using your usual blouse method
after marking the necessary points, from the center of the dress mark 1inch inwards.
place your ready made cup from the marked point(1inch mark) towards the arm hole.
the bust cup should rest on the under bust point.
trace it out. Add extra ½inch for sewing allowance.
cut it out. Place on your material and cut out.
I'm not done with the dress but this post is just to show you how to go about corset cutting.
You can see the corset already!