At the end of the previous step, you had nine strips of nine squares.
Now, snip away the extra thread at the top and bottom of each seam.
Then, iron! Lots of ironing. Or, to be accurate, “pressing” – vertical action, not horizontal.
Right side up.
Fold each seam back. Press each seam to set the seam.
Then press the fabric toward the darker fabric (you have to alternate each row, if you don’t have a black checkerboard pattern like I do).
Make sure there are no folds at the seam.
Lay everything out to make sure it looks nice.
There ends Lesson 3 Chapter 4.