The HST rows are to suppose to fit the width and length of the main part of the quilt. You will need to re-do them because you are a little short of the corner. Then put a brown square on each corner the same size as the HST.
Your HST are going in the opposite direction then the pattern picture. If you turned them in the direction in the pattern you would put a blue square in the corner.
Does this help?
Next row is a solid color strip, yours would be blue, then another row of HST that fit from corner to corner with a solid block on each corner. (The corner block is the same fabric as the edge it will be sewn to)
BTW-Beautiful Quilt!