Step Four: Attaching the back
Open the piece you just sewed with the seams showing or right side down.
Get you back piece and make sure you have applied stretchable fusible interfacing. Find the middle of the back neckline by folding the back piece and place a pin there.
Pin the back to the neckline and sew at 3/8″. Finish the seam with a three step zig zag or a serger.
Step Five: Attaching the sleeves
Attach fusible stretchable interfacing to the hem on the sleeves. Serge or zigzag the sleeves seam allowances. Mark the back of the sleeve so you know what way the sleeve must be sewn. I will use a pin because my fabric unravels very easily so I can't make a notch.
Spread the cardigan wrong side up, or with the seams showing. The front and back will be on the sides and the armhole in front of you. On the picture below, the back is on the right and the front is on the left. Pin the sleeve to the arm hole starting at the ends. Sew the sleeve to the armhole at 3/8″.