if you have N samples in time with Ts(Time sampling or samping rate) so you can write the time like
t=(0:N-1)*Ts;
in the frequency demain, you have Fs=1/Ts, and you have Nfft=1024, so the frequency can be written like
f=(0:Nfft-1)*Fs/Nfft.
Now you can plot your data in time & frequency...