What you need is this. You'll find its derivation in any standard thermodynamics text.
[itex]\left(\frac{\partial U}{\partial V}\right)_T = T\left(\frac{\partial P}{\partial T}\right)_{V}  P.[/itex]
I agree, though, with Studiot. It is impolite not to acknowledge attempts to help. It's perfectly in order to add that you didn't understand the post, but better if you can say exactly what you didn't understand.
