I think I have a grasp on DMing now but I'm stuck on these specific NPC/Monsters.

We are doing the Strahd campaign and in the crypt you get backstories to each person in the crypt. Is that just for me or how do I work that into the story for the adventurers. With immediate attacks and not really anything in the crypts to give those backstories I can't figure out how to give that knowledge to everyone else, if it's even needed.

I don't mind adding my own stuff so that they can get this information too. But I have no ideas that would make sense as to why it would even be there.

Thanks!

Having run Strahd myself I found most of that stuff is just flavour for the DMs benefit rather than anything the players will ever learn. In a normal setting I'd usually as for a History roll to see if the characters recognise the names but the whole point of CoS is Barovia being cut off so there's no way they would recognise anything. I think it just falls under the old adage that players only ever learn a fraction of the lore and care about even less of it

Well you read the names of all of the crypts on the inscription on the door. Most of these names don't really have relevance, but give flavor and context for the rooms to come. Sometimes these names actually do have relevance depending on what you set up in the story, for example, the characters in my campaign heard about saint Markovia, killing a band of werewolves with nothing but a thighbone. You can guess how they react when they see said thighbone. 

The kind of names appearing on the doors don't actually need backstories though, it's mainly foreshadowing for what's in the crypt.