At back (lacing) sew parts of coutil together with the sateen ribbon between. Open seam allowance, iron. Fold in upper and lower seam allowance of facing. Fold sateen ribbon around edge of coutil and sew like side part. Sew tunnels, leave open upper edge.
The busk part is a little bit more complicated to sew. At the right front edge mark Position for the loops. Sew front edge, skip gaps at right edge, sew along left front side without gaps.
At upper and lower edge of busk part mark end of busk, ad about 3/16″ (1/2cm) and sew with small stitches. Cut back seam allowance and turn inside out. Insert busk, at left side mark Position for the posts. Make holes with an awl an pop posts through the holes.
Fold sateen ribbon around coutil edge, sew like side part and lacing part. Sew busk in place, use your Zipper foot and sew as close as possible.
At back part mark Position for the grommets and insert them. Insert boning, close upper edges. Insert lacing.
If your corset hits you at the breast bone sew a little pad and fix it with some stitches at the upper edge of the busk. Finished!