Before fdtd, simple differentitation?

I need an example to learn the basics of how to apply numerical diff. using matrices. I mean i want to plot "u(x) vs x" figure where for example d^2u/dx^2=f(x) and boundary values are given for example u(0)=0 and u(1)=10. I need to do this in matlab. I was able to do it before but using iterative methods. But i forgot the subject a bit. There were also first derivative of u(0) was needed as boundary value. So anybody can help me because i'm confused.