You should solve it numerically.

can be break into two first order differential equation

and

You should know the initial condition and

With Euler's method:

It means that and can be calculated from and

The time step need to be small enough to avoid accumuation of numerical error.

There are better numerical method to solve it. e.g. Runge-Kutta 4th order.

I think you are learning it right now? Right?