STFT signal using the spectrogram function

Hello all,

I am a bit new to signal analysis and my understanding is slightly limited so apologies if this is too trivial. Here it is.

Assume I have removed a trace from an external software for a signal I am interested to transform using STFT. The data I have are simply 1 array containing Amplitudes and a second corresponding to time points. I tried to use the standard spectrogram function to plot the graphs thinking that I would do the trick but that would only include the amplitude values with no reference to time and the results come out without me controlling all data. So in any case if I have a sample size of 251 with a total sample time of 30ns (so my sample frequency is 8.36Ghz) how should I proceed to plot my spectrogram?

Thanks Theo