Question: Please help with creating a procedure

Hi,

I am trying to write a procedure for this problem that I am trying to modle in maple. but I am really stuck. I know how to do the problem by hand but I have no idea how to modle it using the maple embedded components.  I was wondering if anyone can give me a headstart on where to begin and stuff. Here is the problem:
I am trying to model how rapidly(dh/dt) the fluid inside a vertical cylindrical tank drop if we pump the fluid out at a certain rate.
(I am suppose to create the procedure and put it in the embedded components in maple, so that the person can be cable to chose a rate  that the water is being pumped out of the tank(dv/dt), chose a a certain dimension of the cylinder, and then the code is suppose to give your the specific rate at which the water inside the tank  drops(dh/dt))
I know that   Volume of a cylinder is =Pi*r^2*h. and when you integrate it is:
    dv/dt =Pi* r^2*dh/dt (is the radius doesnt change as time goes on)
so dh/dt = (dv/dt)/(Pi*r^2)
but this is as far as I have gotten with this problem. but I have no idea how to do the procedure in maple. if anyone can please give me a headstart or at least explain step-by-step how i can do the procedure. that would be wonderful
Thanks in advance
Jessica