You either have it or you don't.  You can learn to be funny, but it never really is the same.  Look at the funny people around you, they don't think about it, it just comes naturally.  Now if you, who I am assuming has is a serious type person tried to do the same thing, it would not come off sounding natural.  Be happy for who you are.  Laugh at the things around you.  This will relax you enough that you may be able to pick up on some "humor vibes".  Good luck.