Don't apologize for asking questions! The only dumb question is the one you don't ask.
Hens do not sit according to whether or not eggs are fertile, but rather simply when the fancy strikes them. There are some people who will tell you a Silkie will happily attempt to brood golf balls and rocks, and I don't doubt it either.
Generally speaking, all Silkies go broody. I haven't yet met one that isn't broody. That's not to say they don't exist, but I've never encountered them. Like most hens, Silkies must mature before they are likely to begin brooding. Most chickens begin brooding after at least 1 year of age but an 8 or 10 month old broody is not unheard of, especially in Silkies and similarly broody breeds.
To tell if an egg is fertile, you must crack it. A small white bullseye on the yolk means it is fertile; a small, misshapen white dot means it is not. The next time you make some breakfast break the eggs into a bowl and check each of them. Chances are if two or three are fertile, the rest will be as well. You may have to turn the yolk over a few times to see the dot, but be careful not to break it, as the white dot disappears after its broken.
