Ghosts are post-living supernatural beings that are formed by the disembodied souls of once-living humans. A ghost is created when a human being dies before they can resolve certain issues in their lives. Spirits appear immediately upon the death of the person, in the same clothes that they were wearing at the moment of their death.
A ghost will only be allowed to pass on to the next life if they have overcome the issue that is keeping them on Earth, or if magical means are used against them. If a spirit has strong unfinished business, it will keep them from seeing the Angel of Death who is supposed to take them to the other side. That being said, someone can also refuse to go with Death which will result them in being stuck as well. Death appears to a person as someone who they love or any comforting presence in order to make them willing to go with them. The details of the afterlife are not clear, but when the Spirit is ready, a door will appear to them that Death will then walk with them through to go to the 'other side'.
A Vampire and Werewolf are damned souls and it is unknown where they end up when they die.
Ghosts have multiple abilities that range from telekinesis to possession. It all depends on the Spirit themselves as there are different types such as poltergeists, vengeful spirits, etc.