The glueing is done with a spray gun and contact cement. You can do it with a can of 3m spray adhesive. Peel off the Grey cloth, coat the foam piece and the new fabric, lay it out and smooth it out... replace headliner... drink celebratory beer...repeat final step as necessary. This is a 1, on a scale of 1-10, on difficulty. Have at it with all confidence, you can do it.