According to The Book, you’d use a single bias application to “finish and strengthen a raw edge and also to add a decorative trim to a garment. In some cases it may replace a facing at the neckline, sleeve, or armhole edges.”
Begin by preparing your strips. You’ll want a 1.5 inch wide strip for a single bias tape.
Lay right side of bias tape to wrong side of main fabric, so both have wrong sides up. Match raw edges to each other.
Fold bias strip in half to the right side of the main fabric, just covering the first stitchline