Solving 2nd order differential equation in MATLAB?

I have the following equation:

d2X/dt^2=-c1*dX/dt-c2*X+c3*sin(c4*t)

Where c(1-4) are constants.

I'm having problem entering the equation in my function m-file as don't know how to do it with dX/dt and X as well as with the function sin(t).

Main problem is then how will I get MATLAB to understand that dX/dt = D(X)

And that sin(t) is a function of time (no time vector inside function as I will use it in Ode45).

Should I try and break up the equation in some way or can i enter it as whole?

I hope you get my questions :)

Thanks in advanced!