Japanese Possessives?

I've noticed sometimes the Japanese use "no" and I think in the book i'm reading, it said that particle is used to show ownership. But what i'm confused in all this is since thats a book and i can't ask a book questions so here it goes :

if i were to say "It's Kumiko's Book", would that be translated to something like :

"Kumiko-san no hon desu"

am I learning or...? Thanks!

Your translation is correct.... if that's what you were asking....