Step 1 – Bring the needle and thread up at 'a' as shown.
Step 2 – Insert the needle at 'b' and pick up a small stitch as shown and pull the needle.
Step 3 – Keeping the working thread up pick up a small stitch c-b as shown and pull the needle.
Step 4 – Insert the needle at 'd' and pick up a small stitch as shown and pull the needle.
Step 5 – Keeping the working thread down pick up a small stitch e-d as shown and pull the needle.
Step 6 – Repeat steps 2,3,4 and 5.