Video Tutorial
Make a granny square of 50 rows.

Bend the granny square by the middle. Place a marker at 20cm from the bended part.
Sew the sides from the corners to the marker
EDGE
Place the yarn on the neck round
Row 1: 1 double crochet around
Rows 2 -8: *2 front post double crochet, 2 back post double crochet* Repeat around
Repeat the same edge on the 2 sleeves rounds