Also what preparations I have to do and what paint I should use to paint them white.
Check a tiny piece with a knife, if they were painted, then the paint will scratch off… if stained it will not (unless you really go deep into the wood) … if stained and varnished, then the varnish will also scratch off but will be a more flaky looking residue… so …to paint them you should prime them first using an oil base sealer-primer (or use a pigmented shellac sealer primer… which will dry much faster) … then paint with one heavy coat of Sherwin Williams paint (use a semi gloss finish on woodwork… color of choice) … See my site on this here: http://www.Paintahouse.com
Thank you so much for your reply. Greatly appreciated.
By the way, do I have to sand off the old stain/ varnish before applying priming? Other websites suggested that the moldings should be sanded by 180 grit sandpaper and clean thoroughly before applying prime.I will trust your instruction!