Paint it with chalk paint and then distress. Annie Sloan makes a paint color called Old White. Perfect for making chairs look old. Seal the chalk paint with a waterbased clear poly soo it doesn't yellow over time.
Rub it down, use dry brush method and paint it with white emulsion paint. Don't give it a dense all over colour , do it roughly, and when dry rub back some areas. Use either clear or antique wax to seal it. Enjoy the process!
Whst type of finish do you have now - paint, stain? You will spend more time prepping the surface than actually painting. Clean the chair really well first. You want it dust and wax free. If there is a glossy finish, sand it to remove the shine before painting.