Now what? You've started attaching the inside arm of that Goodwill chair, but you have no clue how to get that rolled arm pleated and finished. See how the pros do it, step-by-step.
Starting at the curve on the inside, form a tight pleat by folding the fabric over and using the regulator, or long needle. to make it crisp. This is the second pleat moving towards the top of the arm.
Hold the pleat in place and secure with the staples or tacks.
Cut excess fabric off under each pleat as you go.
When you get to the outside of the rolled arm, remove the baste (or set) tack and readjust the fabric, pulling forward and down to remove slack. Staple in the last pleat and then staple the rest of the fabric snugly around the arm.
The outside arm will attach and be stapled on the front and a fabric covered panel (probably with cording) will be attached on the front of the rolled arm.
Masters at work, a joy to watch and learn.