Here's a bit more info on how film speed, shutter speed and aperture are related.

Start off with your film speed on a bright sunny day...
If your film is iso400 try these settings

Shutter speed is aproximatly 1/iso gives 1/400 but camera shutter speed which is the closest is 500 that translates to 1/500 of a second.
Aperture should be set on f16 for the bright sunny day.

So shutter 500 and aperture set on f16 allows a certain amount of light to hit your film and make the correct exposure.

There must be more to it than that you say...
Well...

If you were to change your shutter speed to 1/1000 (1000 on shutter speed setting) and
change your aperture to f11, you will allow the exact same amount of light to strike the film...

It is one shutter speed FASTER to give 1/2 the time for light to hit the film BUT...
it is also one f stop opening larger (bit confusing because smaller f stop opens up the blades in the lens more) allowing 2x the light to pass through the lens...

Final result... 1/2 the time by 2x the lens opening gives same exposure!

You will soon learn why we chose different shutter speed and f stop combinations for particular photos to accentuate what we are trying to show in our photos.

Hope this makes sense to you...

It is intended to give you some info one spoonful at a time.

Welcome to APUG from another Noobe to this site.