Questions about this piece
How do you tie a scarf onto a handbag?
Knot it at the base of the handle, where the handle meets the bag. That spot holds, and it stays out of the way when you reach inside. Narrow the scarf into a band first so it doesn't bunch, and use a square knot rather than a bow, which works itself loose against a smooth handle. Leave a few inches of tail showing. A square bandana like this one suits the job, because the ends taper once it's folded down and the knot lies flat.
How do you get wrinkles out of a scarf?
Steam it, don't iron it. A printed scarf is a single thin layer, and most are synthetic, so direct heat from an iron can glaze the surface and leave a permanent shine. Hanging it in the bathroom while you shower, or passing a handheld steamer a few inches off the fabric, relaxes the creases without touching the print. If you do reach for an iron, use the lowest setting with a cloth in between. A single-layer square like this one drops out fast either way.
How big is this bandana?
About 27.5 by 26.5 inches, so near enough a true square. That size is what buys you options: rolled from a corner-to-corner fold it makes a band long enough to circle your neck with length left to knot, and opened out it is still wide enough to fold into a triangle and tie under your chin. A 20-inch square only really manages hair.