The first step is to get 1/2 yard of any color jersey. The first time I did this I was FREAKING out about sewing with knit, but honestly it is super simple! I just increase my stitch length and it works perfectly. If you use a serger just change it to a knit setting, easy peasy. Using a double needle gives jersey a more professional look, but I like the rows of stitching on this scarf a little further apart so I didn't use it on this project. So don't be scared! I do recommend practicing on a scrap first first.
I always iron my jersey first, seems weird I know, but it does help. Fold the 1/2 yard piece in half lengthwise, so you end up with a 9" x45" rectangular strip. Sew/serge the edges shut leaving a gap to turn it right side out. Flip it out, iron it and sew the opening shut. Now you have a lovely long rectangle. Thrilling, I know.