Fastfire II mounting question...

[mossyoakpro]

This sighting system is totally new to me so I have a few questions....

1) Does the base for the sight bolt directly onto the top of the shotgun without a Picatinney rail?
2) After bolting the base onto the gun does the sight bolt onto this directly?
3) Lastly, where does the guard like you would buy on this website go onto the sight.

Sorry for asking what seems like ignorant questions but up until this year I have been able to shoot with open sights but my eyes have gone south so it is time for a optic of some sort.

Thanks for your help!!