In mass spectrometry, we start with the analysis of the summary formula, e.g. C6H6 can be an aliphatic compound with 4 double bonds (see eg formula proposed for benzene by Archibald. S. Couper in 1858), a ring compound (1 ring) with three double bonds, etc.
Then we match the mass ions from our spectrum to the probable structures from our summary formula analysis using the fragmentation laws of mass spectrometry.
It takes a lot of hard work to start with.
And then it will take you a few seconds to decode such a simple mass spectrum. Once you have a reasonable structure proposal, you can compare it with the spectra in the databases.