How to solve the equation x - sin(x) = (8Q)/(d^2 U) to x

Hi guys,
First off all, Q, d, U are all constants, wich means that the only variable is x, and it varies between [0, pi(3.1416...)]
Secondly, I've already tried used the Newton's Raphson method, but I think I did something wrong(I searched on google how to, but it didn't work for me me).
Lastly, I don't know how to program in VBA but I think it would be helpful to have a small program that's able to solve this kind of equaitions.
Can anyone help me with this?