where to take a certification test

Hi, I'm new. You all can call me Tristan. I am a 28 year old certified nurse assistant! (That means I get to take care of people :3!! Yayy) I specialize in so I can also help others get their certification!! I'm obviously new here, but I somehow came across this place searching for after work.. weird! haha but I though this place seemed cool, so I figure I might as well join.