First of Necromancy is NOT Black Magick, it is NOT Pure Evil and other bull that people who pretends to know a lot in magick would say.
Though yes Necromancy can be used to harm but then again an innocent wish spell can turn evil. Necromancy is sometimes called Negromancy or Nigromancy, death being something traditionally associated by the colour black therefore negro meaning black.
Necromancy is spiritual divination - in short any magick that involves spirits and demons etc. Necromancy varies from culture/religion to culture/religion. For example I practice ancestral worshipping, that can be seen as practicing Necromancy and I don't deny the fact that I do, I was raised to practice Necromancy due to my culture. But there is a little bit of Necromancy in almost every religion, for example in the bible when Jesus was resurrected, no matter how much catholics and christians etc. deny it, its really hard to not believe thats got anything to do with magick at all.
Anyways back on topic, I believe Necromancy to be a very broad term. Necromancy is the art of summoning (or exorcising spirits) to predict future, to do their bidding and for other things but having said that necromancy is not something easy to master, in fact I would think it to be extremely hard to master because you would need a strong understanding of other forms of magick to start you off, you would need to have an advance understanding in herbalism and the elements. And depending on the culture or religion your learning from there's more to it.
I suggest you do some researching of your own first (better with books because there's a lot of bull on the internet on necromancy), and if you're a beginner then I think its better you get started on the basics first before starting Necromancy.
Necromancy is the art of working with death energies. This includes contacting and communing with the dead, magically working with those who have passed on, and even honoring those who have passed.
Have you ever tried of making your own?? Making your own spells and rituals for any kind of magick is better and gives you more energy and will for your spell to work better.
If your learned any of the basics then your good to go and i've never messed or looked into Necromancy but i have heard about it some.
And you shouldn't be casting spells you don't know how to do.
I personally believe necromancy is devided into two areas: Traditional necromancy and spirit necromancy. Spirit necromancy is when a caster summons a spirit via rituals and spells involving summoning, binding and banishing chants and a protective circle, it does not involve a corpse in anyway. Traditional necromancy involves physical manipulation/mutilation of the deceased persons corpse and forcing the spirit inside to talk through its old mouth. In most senarios the spirit is going to be angry and when angry, vey powerful, this is what makes necromancy so dangerous. Ive heard about people using death energies to cause harm to the living, im bot entirely sure if this is true but it does sound interesting.
I would say that both of those fall more into the realm of "traditional necromancy," though in truth the mutilation/use of a corpse was often used for other purposes beyond anything actually involving the dead.
The most common example actually spoken of these days is the Hand of Glory... a human hand used with tallow candles made from the fat of a hanged man, I believe, that was used for various nefarious purposes.
This particular item, using items from a corpse, has nothing to do with necromancy.
Traditional necromancy involves the summoning of the spirits of the dead, almost exclusively. Sometimes the bodies and so forth are used to this purpose. Sometimes blood sacrifices are offered (the blood of a ram, for example). Etc. These offerings are often used to appease the dead. To this end, other more pleasant offerings are made, usually of a personal nature to the spirit being called.
In more modern practice we also see the practice of death magic, as it is called, incorporated into the necromantic arts. Death magic, the magic of change, can be used to offer a great deal of personal growth and beneficial effects for those who are involved with it, contrary to the somewhat frightful image that its name creates.