A spherical balloon is being inflated and the radius of the balloon is increasing at a rate of 2 cm/s...?

I have the following math question--- it's the only one I have left. Please do NOT give me the answer. I just need someone to walk me through what I need to do to solve it, or at least point me in the right direction. I really want to understand this calculus problem and it's really cold and snowing really hard outside, otherwise I would walk to the math lab on campus and get some help. If you could guide me for the first few steps or offer any help, I would appreciate it!

A spherical balloon is being inflated and the radius of the balloon is increasing at a rate of 2 cm/s.

Express the radius of the balloon as a function of the time (in seconds). You may assume that at time 0, the radius is 0.

If V is the volume of the balloon as a function of the radius, find the composition "Vor" (like finding f of g, but with v of r, and r being radius)

Note that Vor represents the volume of the balloon as a function of time.

So there's technically two questions, but if I understood the first one, I could do the second one easily I think, since it's just a composition of functions. Thank you!