Our daughter was born in Florida and her father and I now live on Colorado. How do we go about adding him to the birth certificate even though it has been 6 years?

I'm not sure about Colorado or Florida, but here in Nebraska, the father would need to prove paternity (they allow so much time to pass before requiring this), file the paperwork and pay a fee. The best route is to contact the Vital Records Bureau in Florida and ask them. They should be able to tell you what would need to be done, such as if proving paternity is needed or if it is just a matter of filing out paperwork and paying a fee.