I stay in Louisiana and I'm trying to get my son's last name change to my last name, I'm the biological father and I pay support and spend time with my kids. She's just being hateful. So how or what do I need to do.

You can try and file a motion in family court to force mom to allow it, but it is very doubtful,

Merely doing your required duty ( paying support, it is not like you really have a option on that)

And just doing your moral duty, spending time with the kids.

I will assume the child never had your name, and you are not listed on the birth certificate.?

But it is common for the child not to have fathers name, and often there is nothing the father can do