You may also have to remove some of the upper a, b, c pillar panels to get the headliner to drop form the roof area. You may have to unscrew some bolts and/or pry some parts up with a flathead or torx screwdriver.
[header] How to install a headliner [title] Remove the old headliner. [substeps] Pry off all the trim that surrounds the headliner and holds it in place. Detach and remove all of the seatbelt covers, lights, speakers, visors and clothes hangers.