I really hope this makes sense. I’m horrible at explaining things. You’re basically going to want to hem all the edges to they’re not raw and fraying. Then sew your triangle sleeve to the rectangle. Fold the whole thing in half and put it over your shoulder to pin where you want to sew the other side closed for your sleeve. When it’s done you’ll have a hole to put your arm and head through, and the side with the yellow will rest on your shoulder. Then you pull the waist closed and tie with the strip of red fabric.