fft of a complex chirp signal and plot the fft result

Hello scientists. I want to compute fft (fast fourie transform) of a complex chirp signal in matlab. I know that because the signal is complex, I should compute double sided fft. But I do not know how to calculate frequency bins for fft plot of the complex chirp signal. according to niquest theorem if my sampling frequency is Fs, should I remove frequencies higher than Fs/2. So when I have nfft = 256 fft samples, and sampling frequency of 10Mega Hz, how should I calculate frequency bins (espacially start and end of frequency points) for fft plot (amplitude-frequency plot)? thanks for your consideration.