How to get total power from spectrum measure of a signal

[bonzer]

Hi everyone! Please help me to understand how exactly to get the total power of a signal for example that from this figure from a spectrum analyzer.
Forget about that narrow band signal for now and consider only M2 part.

I think I would need to sum all these values through the band. I need the power spectrum density (PSD).
What would it be? The values I see are RMS (right?). Then the PSD in this case would be (as for sinusoids) the power of two of these values (converted in linear scale).

Then should I multiply the almost constant PSD by the band? (assuming I know that there are for example 100Mhz of -3dB band).

Is total power PSD*Band ?