Spatial resolution and spatial frequency resolution

In a 1D fourier transform, fs is sampling frequency and the time resolution T=1/fs. so for a function f(t)=sin(20*Pi*t), the fft code would be

fs=100

N=200

T=1/fs

t = (0:N-1)*T;

x1 = sin(20*pi*t);

Xf=fft(x1);

plot(abs(Xf));

Now for a 2D fft transform, delta m=0.01, and delta n=0.01 M=N=100

f(m,n)=sin(4*pi*m)+cos(6*pi*n). Spatial resolution is 1/delta m and i/delta n. my question is how to do the fft2 of this function.

my m=(0:100)*?

and n=(0:100)*?

I just need to understand what will come in the place of ? for m and n. I can write the fft2 myself.