There has been a "father" the whole time, he signed the birth certificate
Unlikely. Parents don't typically sign birth certificates. Birth certificates are typically signed by the delivering phyisician and a local records clerk.
I would like to know what will happen with the "father" and the mother in the ways of child support for the past 5 yrs when I do a legal paternity test and it reveals that i am the biological father.
Nothing, but I'm curious why you believe this is your child if neither you nor any other man has ever done a paternity test.
Also will I have to pay any money as I have just recentley found this out?
You very likely will have to pay for any paternity test that you initiate.
Can the child be mine?
Well...you told is that the child IS yours, so.... Beyond that, however, we obviously have no knowledge about this one way of the other.
Any information would be indeed helpful as I have no idea what to do, I really just want to have my child and be a father.
As mentioned, it's not clear why you think the child is yours, but the smartest thing to do would be to consult with a local family law attorney.