Ignore Valor...everyone else does
When you first start a necromancer, click on the numbers (spell circles) at the bottom of the book to check the required necromancy and mana needed to cast each spell. You'll find that you can only cast light and necro spirits at first.
I recommend going out and hunting with necrospirits, and then, when you have a few spare minutes/hours, sit around and cast light over and over on yourself. Once you get reconstruct, use that while fighting to heal yourself and gain a bit of necro. Hope this helps you get started.
