Partial Differential Eq via Operator Method

Question

I’m a bit lost as to where I should start. The problem asks to find u(x,t) via operator method.

$u_{tt}-u_{xx}=0$

$u(x,0)=0, u_t(x,0)=\pi^2-3x^2$

$u_x(0,t)=u_x(\pi,t)=0$