The particle no is possessive in most senses. If you have watashi no it means "my" (watashi+possessive particle). It can also mean "of;" I'm almost positive of that, but I can't think of any examples off the top of my head. @@; No can also be used to modify a noun into an adjective. ^_^;; Dipping into Yu-Gi-Oh fandom, Yami Yugi is often referred to as Yami no Yuugi. Yami is the word/noun for "darkness". By adding no, it becomes a descriptive adjective. Therefore, you have "Dark Yuugi". ^_^;
Dashes aren't actually there in Japanese. For example, "Sakura-chan" would simply be written Sakurachan (さくらちゃん). Adding the dash when translating or transliterating it is just easier so that people know it's a suffix and not part of the name/subject, I guess.