The sweater is knitted in one piece from side to side.
You start at the left sleeve cuff and end at the right sleeve cuff. The front and back parts are knitted separately, but still connected to the main piece. There is a lot of st at the same time when you do the front or back part. It is therefore a good idea to knit flat with a long circular needle. You can use the same needle all along.
When everything is done, you sew the shoulders and sides together.

Knitting method: Half fishermans rib
No purl with this technique. The wrong side is always knitted. The right side is also knitted, but every second st is knitted in the st below (k1b). This will give a result that looks ribbed but is more porous and not so stretchy. The best of all, it does not curl.

The sleeve increases and decreases forms a decorative fish-bone pattern.

You can use any yarn as long as you get right gauge, but an elastic yarn is not recommended.