You are born with them blocked unless like me you were born absurdly powerful and this is another topic but there are seven BODY chakras but true adepts can cultivate even more. Altoough like I said unless you were born with your chakra s opened you might not be able to open many non body chakras up but a good. Website is joyofsatan.com very informative even if u can't get the taste for black magick. Though don't put this off I think the site might be on its last legs
You can open them through meditation. I've never heard you're born with them closed, but whatever. Try researching different meditations to open your chakras. I don't know which ones are closed, so I don't know exactly what to recommend.