Vampires are described on pages 295 through 298 of the Monster Manual. Strahd himself is described all over the Curse of Strahd book, but his stats are on pages 239 and 240.
Here are some notes about vampires that may not have been clear upon first reading of the above sections.
In General
Vampires are undead, and thus can be targeted with Turn Undead and similar effects.
A stake to the heart while in their resting place will kill a vampire spawn outright, but only paralyzes a true vampire (Strahd included).
Any vampire or spawn can be restored to life and have their alignment returned from Evil if they are killed and brought back to life, or if Wish is cast on them.
Strahd
Strahd differs from normal vampires in the following ways:
- he doesn't need to rest during the day
- he has higher Skill statistics
- he can cast spells
- he has Lair Actions
- he has the Heart of Sorrow
- he is almost always accompanied by minions (CoS p. 239)
Ravenloft is Strahd's Lair, so it would have the regional effects described on page 296 of the Monster Manual.
Vampire Spawn
A spawn who drinks its master's blood becomes its own, free vampire.
A spawn's bite cannot create new vampires.