Bit rate in function of radio frequency
To calculate this you can use the Shannon–Hartley theorem.


  $$C =  B \log_2 \left( 1+\frac{S}{N} \right) $$
  
  where 
  
  C is the channel capacity in bits per second;  B is the bandwidth
  of the channel in hertz (passband bandwidth in case of a modulated
  signal);  S is the average received signal power over the
  bandwidth (in case of a modulated signal, often denoted C, i.e.
  modulated carrier), measured in watts (or volts squared); N is the
  average noise or interference power over the bandwidth, measured in
  watts (or volts squared);  and S/N is the signal-to-noise ratio
  (SNR) or the carrier-to-noise ratio (CNR) of the communication signal
  to the Gaussian noise interference expressed as a linear power ratio
  (not as logarithmic decibels).


In a simple case, your maximum bandwidth will be the frequency you use. More likely it will be whatever frequency you modulate your signal at. 

If your system were perfect, that would also be your channel capacity. But, it won't be perfect, ever. There will be noise and signal loss, more than you want. 

You'll have to give more information about your system before you can get a reasonable first cut of your actual channel capacity.

To address your follow up question:

As an engineer, I like to draw straight lines and pretend they're close enough to the real world. For a situation like this, where a whole mess of small (and a few large) losses come into play, I would make a Fermi estimate.
I understand that's not easy. One of the biggest problems for aspiring engineers is they're not willing to just guess. This prevents them from moving forward, likely failing, and returning to make a better guess. Just get some paper and sit down in a place where you can make some noise and say "eehhuuhhhmm, fifty-six... ish?". Write that down. Now calculate it. Does it make any sense? Use whatever information you have; if your calculations show that you can set up your own radio station with some AA batteries then get a new piece of paper. 
In the end the system you're trying to model is really complex; clearly, it depends on undulating ionospheric plasma and the time of day. You'll likely be able to guess your values within an order of magnitude, which might be enough information to get you to start building something.